<?xml version="1.0" encoding="US-ASCII"?>
<!--XBRL Document Created with Wdesk from Workiva-->
<!-- -->
<linkbase xsi:schemaLocation="http://www.xbrl.org/2003/linkbase http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd" xmlns="http://www.xbrl.org/2003/linkbase" xmlns:xbrldt="http://xbrl.org/2005/xbrldt" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
  <roleRef roleURI="http://www.mistrasgroup.com/role/AccountsReceivableNet" xlink:href="mg-20160831.xsd#AccountsReceivableNet" xlink:type="simple" />
  <roleRef roleURI="http://www.mistrasgroup.com/role/AccountsReceivableNetDetails" xlink:href="mg-20160831.xsd#AccountsReceivableNetDetails" xlink:type="simple" />
  <roleRef roleURI="http://www.mistrasgroup.com/role/AccountsReceivableNetTables" xlink:href="mg-20160831.xsd#AccountsReceivableNetTables" xlink:type="simple" />
  <roleRef roleURI="http://www.mistrasgroup.com/role/AccruedExpensesAndOtherCurrentLiabilities" xlink:href="mg-20160831.xsd#AccruedExpensesAndOtherCurrentLiabilities" xlink:type="simple" />
  <roleRef roleURI="http://www.mistrasgroup.com/role/AccruedExpensesAndOtherCurrentLiabilitiesDetails" xlink:href="mg-20160831.xsd#AccruedExpensesAndOtherCurrentLiabilitiesDetails" xlink:type="simple" />
  <roleRef roleURI="http://www.mistrasgroup.com/role/AccruedExpensesAndOtherCurrentLiabilitiesTables" xlink:href="mg-20160831.xsd#AccruedExpensesAndOtherCurrentLiabilitiesTables" xlink:type="simple" />
  <roleRef roleURI="http://www.mistrasgroup.com/role/Acquisitions" xlink:href="mg-20160831.xsd#Acquisitions" xlink:type="simple" />
  <roleRef roleURI="http://www.mistrasgroup.com/role/AcquisitionsAcquisitionRelatedExpenseDetails" xlink:href="mg-20160831.xsd#AcquisitionsAcquisitionRelatedExpenseDetails" xlink:type="simple" />
  <roleRef roleURI="http://www.mistrasgroup.com/role/AcquisitionsDetails" xlink:href="mg-20160831.xsd#AcquisitionsDetails" xlink:type="simple" />
  <roleRef roleURI="http://www.mistrasgroup.com/role/AcquisitionsPreliminaryPurchasePriceAllocationDetails" xlink:href="mg-20160831.xsd#AcquisitionsPreliminaryPurchasePriceAllocationDetails" xlink:type="simple" />
  <roleRef roleURI="http://www.mistrasgroup.com/role/AcquisitionsTables" xlink:href="mg-20160831.xsd#AcquisitionsTables" xlink:type="simple" />
  <roleRef roleURI="http://www.mistrasgroup.com/role/CommitmentsAndContingencies" xlink:href="mg-20160831.xsd#CommitmentsAndContingencies" xlink:type="simple" />
  <roleRef roleURI="http://www.mistrasgroup.com/role/CommitmentsAndContingenciesDetails" xlink:href="mg-20160831.xsd#CommitmentsAndContingenciesDetails" xlink:type="simple" />
  <roleRef roleURI="http://www.mistrasgroup.com/role/CondensedConsolidatedBalanceSheets" xlink:href="mg-20160831.xsd#CondensedConsolidatedBalanceSheets" xlink:type="simple" />
  <roleRef roleURI="http://www.mistrasgroup.com/role/CondensedConsolidatedBalanceSheetsParenthetical" xlink:href="mg-20160831.xsd#CondensedConsolidatedBalanceSheetsParenthetical" xlink:type="simple" />
  <roleRef roleURI="http://www.mistrasgroup.com/role/DescriptionOfBusinessandBasisOfPresentation" xlink:href="mg-20160831.xsd#DescriptionOfBusinessandBasisOfPresentation" xlink:type="simple" />
  <roleRef roleURI="http://www.mistrasgroup.com/role/DescriptionOfBusinessandBasisOfPresentationAdditionalInformationDetails" xlink:href="mg-20160831.xsd#DescriptionOfBusinessandBasisOfPresentationAdditionalInformationDetails" xlink:type="simple" />
  <roleRef roleURI="http://www.mistrasgroup.com/role/DescriptionOfBusinessandBasisOfPresentationPolicies" xlink:href="mg-20160831.xsd#DescriptionOfBusinessandBasisOfPresentationPolicies" xlink:type="simple" />
  <roleRef roleURI="http://www.mistrasgroup.com/role/DocumentAndEntityInformation" xlink:href="mg-20160831.xsd#DocumentAndEntityInformation" xlink:type="simple" />
  <roleRef roleURI="http://www.mistrasgroup.com/role/EarningsPerShare" xlink:href="mg-20160831.xsd#EarningsPerShare" xlink:type="simple" />
  <roleRef roleURI="http://www.mistrasgroup.com/role/EarningsPerShareDetails" xlink:href="mg-20160831.xsd#EarningsPerShareDetails" xlink:type="simple" />
  <roleRef roleURI="http://www.mistrasgroup.com/role/EarningsPerShareTables" xlink:href="mg-20160831.xsd#EarningsPerShareTables" xlink:type="simple" />
  <roleRef roleURI="http://www.mistrasgroup.com/role/FairValueMeasurements" xlink:href="mg-20160831.xsd#FairValueMeasurements" xlink:type="simple" />
  <roleRef roleURI="http://www.mistrasgroup.com/role/FairValueMeasurementsDetails" xlink:href="mg-20160831.xsd#FairValueMeasurementsDetails" xlink:type="simple" />
  <roleRef roleURI="http://www.mistrasgroup.com/role/FairValueMeasurementsTables" xlink:href="mg-20160831.xsd#FairValueMeasurementsTables" xlink:type="simple" />
  <roleRef roleURI="http://www.mistrasgroup.com/role/Goodwill" xlink:href="mg-20160831.xsd#Goodwill" xlink:type="simple" />
  <roleRef roleURI="http://www.mistrasgroup.com/role/GoodwillDetails" xlink:href="mg-20160831.xsd#GoodwillDetails" xlink:type="simple" />
  <roleRef roleURI="http://www.mistrasgroup.com/role/GoodwillTables" xlink:href="mg-20160831.xsd#GoodwillTables" xlink:type="simple" />
  <roleRef roleURI="http://www.mistrasgroup.com/role/IntangibleAssets" xlink:href="mg-20160831.xsd#IntangibleAssets" xlink:type="simple" />
  <roleRef roleURI="http://www.mistrasgroup.com/role/IntangibleAssetsDetails" xlink:href="mg-20160831.xsd#IntangibleAssetsDetails" xlink:type="simple" />
  <roleRef roleURI="http://www.mistrasgroup.com/role/IntangibleAssetsTables" xlink:href="mg-20160831.xsd#IntangibleAssetsTables" xlink:type="simple" />
  <roleRef roleURI="http://www.mistrasgroup.com/role/LongTermDebt" xlink:href="mg-20160831.xsd#LongTermDebt" xlink:type="simple" />
  <roleRef roleURI="http://www.mistrasgroup.com/role/LongTermDebtAdditionalInformationDetails" xlink:href="mg-20160831.xsd#LongTermDebtAdditionalInformationDetails" xlink:type="simple" />
  <roleRef roleURI="http://www.mistrasgroup.com/role/LongTermDebtScheduleOfLongTermDebtDetails" xlink:href="mg-20160831.xsd#LongTermDebtScheduleOfLongTermDebtDetails" xlink:type="simple" />
  <roleRef roleURI="http://www.mistrasgroup.com/role/LongTermDebtTables" xlink:href="mg-20160831.xsd#LongTermDebtTables" xlink:type="simple" />
  <roleRef roleURI="http://www.mistrasgroup.com/role/PropertyPlantAndEquipmentNet" xlink:href="mg-20160831.xsd#PropertyPlantAndEquipmentNet" xlink:type="simple" />
  <roleRef roleURI="http://www.mistrasgroup.com/role/PropertyPlantAndEquipmentNetDetails" xlink:href="mg-20160831.xsd#PropertyPlantAndEquipmentNetDetails" xlink:type="simple" />
  <roleRef roleURI="http://www.mistrasgroup.com/role/PropertyPlantAndEquipmentNetTables" xlink:href="mg-20160831.xsd#PropertyPlantAndEquipmentNetTables" xlink:type="simple" />
  <roleRef roleURI="http://www.mistrasgroup.com/role/SegmentDisclosure" xlink:href="mg-20160831.xsd#SegmentDisclosure" xlink:type="simple" />
  <roleRef roleURI="http://www.mistrasgroup.com/role/SegmentDisclosureFinancialInformationBySegmentDetails" xlink:href="mg-20160831.xsd#SegmentDisclosureFinancialInformationBySegmentDetails" xlink:type="simple" />
  <roleRef roleURI="http://www.mistrasgroup.com/role/SegmentDisclosureRevenuesByGeographicAreaDetails" xlink:href="mg-20160831.xsd#SegmentDisclosureRevenuesByGeographicAreaDetails" xlink:type="simple" />
  <roleRef roleURI="http://www.mistrasgroup.com/role/SegmentDisclosureTables" xlink:href="mg-20160831.xsd#SegmentDisclosureTables" xlink:type="simple" />
  <roleRef roleURI="http://www.mistrasgroup.com/role/ShareBasedCompensation" xlink:href="mg-20160831.xsd#ShareBasedCompensation" xlink:type="simple" />
  <roleRef roleURI="http://www.mistrasgroup.com/role/ShareBasedCompensationAdditionalInformationDetails" xlink:href="mg-20160831.xsd#ShareBasedCompensationAdditionalInformationDetails" xlink:type="simple" />
  <roleRef roleURI="http://www.mistrasgroup.com/role/ShareBasedCompensationPerformanceRestrictedStockUnitsActivityDetails" xlink:href="mg-20160831.xsd#ShareBasedCompensationPerformanceRestrictedStockUnitsActivityDetails" xlink:type="simple" />
  <roleRef roleURI="http://www.mistrasgroup.com/role/ShareBasedCompensationPerformanceRestrictedStockUnitsNarrativeDetails" xlink:href="mg-20160831.xsd#ShareBasedCompensationPerformanceRestrictedStockUnitsNarrativeDetails" xlink:type="simple" />
  <roleRef roleURI="http://www.mistrasgroup.com/role/ShareBasedCompensationRestrictedStockUnitAwardsNarrativeDetails" xlink:href="mg-20160831.xsd#ShareBasedCompensationRestrictedStockUnitAwardsNarrativeDetails" xlink:type="simple" />
  <roleRef roleURI="http://www.mistrasgroup.com/role/ShareBasedCompensationRestrictedStockUnitsAwardsActivityDetails" xlink:href="mg-20160831.xsd#ShareBasedCompensationRestrictedStockUnitsAwardsActivityDetails" xlink:type="simple" />
  <roleRef roleURI="http://www.mistrasgroup.com/role/ShareBasedCompensationShareBasedCompensationTables" xlink:href="mg-20160831.xsd#ShareBasedCompensationShareBasedCompensationTables" xlink:type="simple" />
  <roleRef roleURI="http://www.mistrasgroup.com/role/ShareBasedCompensationStockOptionsDetails" xlink:href="mg-20160831.xsd#ShareBasedCompensationStockOptionsDetails" xlink:type="simple" />
  <roleRef roleURI="http://www.mistrasgroup.com/role/SubsequentEvent" xlink:href="mg-20160831.xsd#SubsequentEvent" xlink:type="simple" />
  <roleRef roleURI="http://www.mistrasgroup.com/role/SubsequentEventDetails" xlink:href="mg-20160831.xsd#SubsequentEventDetails" xlink:type="simple" />
  <roleRef roleURI="http://www.mistrasgroup.com/role/UnauditedCondensedConsolidatedStatementsOfCashFlows" xlink:href="mg-20160831.xsd#UnauditedCondensedConsolidatedStatementsOfCashFlows" xlink:type="simple" />
  <roleRef roleURI="http://www.mistrasgroup.com/role/UnauditedCondensedConsolidatedStatementsOfComprehensiveIncome" xlink:href="mg-20160831.xsd#UnauditedCondensedConsolidatedStatementsOfComprehensiveIncome" xlink:type="simple" />
  <roleRef roleURI="http://www.mistrasgroup.com/role/UnauditedCondensedConsolidatedStatementsOfIncome" xlink:href="mg-20160831.xsd#UnauditedCondensedConsolidatedStatementsOfIncome" xlink:type="simple" />
  <arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/all" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#all" xlink:type="simple" />
  <arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-default" xlink:type="simple" />
  <arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-domain" xlink:type="simple" />
  <arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/domain-member" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#domain-member" xlink:type="simple" />
  <arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#hypercube-dimension" xlink:type="simple" />
  <definitionLink xlink:role="http://www.mistrasgroup.com/role/AccountsReceivableNet" xlink:type="extended" />
  <definitionLink xlink:role="http://www.mistrasgroup.com/role/AccountsReceivableNetDetails" xlink:type="extended" />
  <definitionLink xlink:role="http://www.mistrasgroup.com/role/AccountsReceivableNetTables" xlink:type="extended" />
  <definitionLink xlink:role="http://www.mistrasgroup.com/role/AccruedExpensesAndOtherCurrentLiabilities" xlink:type="extended" />
  <definitionLink xlink:role="http://www.mistrasgroup.com/role/AccruedExpensesAndOtherCurrentLiabilitiesDetails" xlink:type="extended" />
  <definitionLink xlink:role="http://www.mistrasgroup.com/role/AccruedExpensesAndOtherCurrentLiabilitiesTables" xlink:type="extended" />
  <definitionLink xlink:role="http://www.mistrasgroup.com/role/Acquisitions" xlink:type="extended" />
  <definitionLink xlink:role="http://www.mistrasgroup.com/role/AcquisitionsAcquisitionRelatedExpenseDetails" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_BusinessAcquisitionLineItems" xlink:label="loc_us-gaap_BusinessAcquisitionLineItems_9EB833F0C8D09FF9239790EFD61D2BD8" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable" xlink:label="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_96844121AE403115950590EFD61D3D61" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_9EB833F0C8D09FF9239790EFD61D2BD8" xlink:to="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_96844121AE403115950590EFD61D3D61" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_BusinessAcquisitionAxis" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_56CAFA908ADF9221745D90EFD61D55C7" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_96844121AE403115950590EFD61D3D61" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_56CAFA908ADF9221745D90EFD61D55C7" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_92D27A47F2672B8E3D3990EFD61D784A_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_56CAFA908ADF9221745D90EFD61D55C7" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_92D27A47F2672B8E3D3990EFD61D784A_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_92D27A47F2672B8E3D3990EFD61D784A" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_56CAFA908ADF9221745D90EFD61D55C7" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_92D27A47F2672B8E3D3990EFD61D784A" xlink:type="arc" />
    <loc xlink:href="mg-20160831.xsd#mg_AcquisitionsinFiscal2017Member" xlink:label="loc_mg_AcquisitionsinFiscal2017Member_B3EAF22C78C9BC3839E190EFD61D22C2" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_92D27A47F2672B8E3D3990EFD61D784A" xlink:to="loc_mg_AcquisitionsinFiscal2017Member_B3EAF22C78C9BC3839E190EFD61D22C2" xlink:type="arc" />
    <loc xlink:href="mg-20160831.xsd#mg_AcquisitionsinFiscal2016Member" xlink:label="loc_mg_AcquisitionsinFiscal2016Member_47809FA39B2F61880F5190EFD61DCBCD" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_92D27A47F2672B8E3D3990EFD61D784A" xlink:to="loc_mg_AcquisitionsinFiscal2016Member_47809FA39B2F61880F5190EFD61DCBCD" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_BusinessCombinationAcquisitionRelatedCosts" xlink:label="loc_us-gaap_BusinessCombinationAcquisitionRelatedCosts_36EC1D1139466034385F90EFD61DC715" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_9EB833F0C8D09FF9239790EFD61D2BD8" xlink:to="loc_us-gaap_BusinessCombinationAcquisitionRelatedCosts_36EC1D1139466034385F90EFD61DC715" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_BusinessCombinationContingentConsiderationArrangementsChangeInAmountOfContingentConsiderationLiability1" xlink:label="loc_us-gaap_BusinessCombinationContingentConsiderationArrangementsChangeInAmountOfContingentConsiderationLiability1_1CB447F054E7BC5F84CD90EFD61DD84D" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_9EB833F0C8D09FF9239790EFD61D2BD8" xlink:to="loc_us-gaap_BusinessCombinationContingentConsiderationArrangementsChangeInAmountOfContingentConsiderationLiability1_1CB447F054E7BC5F84CD90EFD61DD84D" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_OperatingIncomeLoss" xlink:label="loc_us-gaap_OperatingIncomeLoss_B14D96CFCB841282929990EFD61D844C" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_9EB833F0C8D09FF9239790EFD61D2BD8" xlink:to="loc_us-gaap_OperatingIncomeLoss_B14D96CFCB841282929990EFD61D844C" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_BusinessCombinationContingentConsiderationLiability" xlink:label="loc_us-gaap_BusinessCombinationContingentConsiderationLiability_734FED227C21E9FCCC2690EFD61D1E1D" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_9EB833F0C8D09FF9239790EFD61D2BD8" xlink:to="loc_us-gaap_BusinessCombinationContingentConsiderationLiability_734FED227C21E9FCCC2690EFD61D1E1D" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://www.mistrasgroup.com/role/AcquisitionsDetails" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_BusinessAcquisitionLineItems" xlink:label="loc_us-gaap_BusinessAcquisitionLineItems_E50059913E2F324904AC9D49452B7926" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable" xlink:label="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_3D934751ED79BE7C6CFC9D49452AE769" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_E50059913E2F324904AC9D49452B7926" xlink:to="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_3D934751ED79BE7C6CFC9D49452AE769" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_BusinessAcquisitionAxis" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_6F5ACADD1B94833576DB9D49452A8FE3" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_3D934751ED79BE7C6CFC9D49452AE769" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_6F5ACADD1B94833576DB9D49452A8FE3" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_F7014397B4C261DC1AD19D49452A8CB0_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_6F5ACADD1B94833576DB9D49452A8FE3" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_F7014397B4C261DC1AD19D49452A8CB0_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_F7014397B4C261DC1AD19D49452A8CB0" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_6F5ACADD1B94833576DB9D49452A8FE3" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_F7014397B4C261DC1AD19D49452A8CB0" xlink:type="arc" />
    <loc xlink:href="mg-20160831.xsd#mg_AcquisitionsinFiscal2017Member" xlink:label="loc_mg_AcquisitionsinFiscal2017Member_046C57C99D2E5EB189969D49452A906B" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_F7014397B4C261DC1AD19D49452A8CB0" xlink:to="loc_mg_AcquisitionsinFiscal2017Member_046C57C99D2E5EB189969D49452A906B" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_StatementGeographicalAxis" xlink:label="loc_us-gaap_StatementGeographicalAxis_183FB6A38A18494AD6F49D49452A92A0" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_3D934751ED79BE7C6CFC9D49452AE769" xlink:to="loc_us-gaap_StatementGeographicalAxis_183FB6A38A18494AD6F49D49452A92A0" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_SegmentGeographicalDomain" xlink:label="loc_us-gaap_SegmentGeographicalDomain_708B7792BEBB48EF31A39D49452AB3E6_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementGeographicalAxis_183FB6A38A18494AD6F49D49452A92A0" xlink:to="loc_us-gaap_SegmentGeographicalDomain_708B7792BEBB48EF31A39D49452AB3E6_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_SegmentGeographicalDomain" xlink:label="loc_us-gaap_SegmentGeographicalDomain_708B7792BEBB48EF31A39D49452AB3E6" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementGeographicalAxis_183FB6A38A18494AD6F49D49452A92A0" xlink:to="loc_us-gaap_SegmentGeographicalDomain_708B7792BEBB48EF31A39D49452AB3E6" xlink:type="arc" />
    <loc xlink:href="http://xbrl.sec.gov/country/2013/country-2013-01-31.xsd#country_CA" xlink:label="loc_country_CA_725A64AEFB854EBF318C9D49452B2D64" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentGeographicalDomain_708B7792BEBB48EF31A39D49452AB3E6" xlink:to="loc_country_CA_725A64AEFB854EBF318C9D49452B2D64" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_BusinessCombinationAcquisitionRelatedCosts" xlink:label="loc_us-gaap_BusinessCombinationAcquisitionRelatedCosts_3DDF91E77728B72623C79D49452B1B3C" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_E50059913E2F324904AC9D49452B7926" xlink:to="loc_us-gaap_BusinessCombinationAcquisitionRelatedCosts_3DDF91E77728B72623C79D49452B1B3C" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_NumberOfBusinessesAcquired" xlink:label="loc_us-gaap_NumberOfBusinessesAcquired_C49A940F131142A58F349D49452B9518" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_E50059913E2F324904AC9D49452B7926" xlink:to="loc_us-gaap_NumberOfBusinessesAcquired_C49A940F131142A58F349D49452B9518" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_BusinessAcquisitionPercentageOfVotingInterestsAcquired" xlink:label="loc_us-gaap_BusinessAcquisitionPercentageOfVotingInterestsAcquired_C19527C549499CE0C5159D49452B4290" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_E50059913E2F324904AC9D49452B7926" xlink:to="loc_us-gaap_BusinessAcquisitionPercentageOfVotingInterestsAcquired_C19527C549499CE0C5159D49452B4290" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_PaymentsToAcquireBusinessesGross" xlink:label="loc_us-gaap_PaymentsToAcquireBusinessesGross_DD28F207C09785CBB7D59D49452BF644" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_E50059913E2F324904AC9D49452B7926" xlink:to="loc_us-gaap_PaymentsToAcquireBusinessesGross_DD28F207C09785CBB7D59D49452BF644" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_BusinessCombinationConsiderationTransferredLiabilitiesIncurred" xlink:label="loc_us-gaap_BusinessCombinationConsiderationTransferredLiabilitiesIncurred_7D7C0E5A3FE2BEB14F809D5550ACB82B" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_E50059913E2F324904AC9D49452B7926" xlink:to="loc_us-gaap_BusinessCombinationConsiderationTransferredLiabilitiesIncurred_7D7C0E5A3FE2BEB14F809D5550ACB82B" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_BusinessCombinationContingentConsiderationLiability" xlink:label="loc_us-gaap_BusinessCombinationContingentConsiderationLiability_3BF7E3EF5040FA3AFF619D49452B4C51" xlink:type="locator" />
    <definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_E50059913E2F324904AC9D49452B7926" xlink:to="loc_us-gaap_BusinessCombinationContingentConsiderationLiability_3BF7E3EF5040FA3AFF619D49452B4C51" xlink:type="arc" />
    <loc xlink:href="mg-20160831.xsd#mg_BusinessCombinationContingentConsiderationPaymentPeriod" xlink:label="loc_mg_BusinessCombinationContingentConsiderationPaymentPeriod_39A01A9F8A57EF127DC89D49452B9C63" xlink:type="locator" />
    <definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_E50059913E2F324904AC9D49452B7926" xlink:to="loc_mg_BusinessCombinationContingentConsiderationPaymentPeriod_39A01A9F8A57EF127DC89D49452B9C63" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_BusinessCombinationProFormaInformationRevenueOfAcquireeSinceAcquisitionDateActual" xlink:label="loc_us-gaap_BusinessCombinationProFormaInformationRevenueOfAcquireeSinceAcquisitionDateActual_F1E7714886AE5C905D6D9D49452C7F71" xlink:type="locator" />
    <definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_E50059913E2F324904AC9D49452B7926" xlink:to="loc_us-gaap_BusinessCombinationProFormaInformationRevenueOfAcquireeSinceAcquisitionDateActual_F1E7714886AE5C905D6D9D49452C7F71" xlink:type="arc" />
    <loc xlink:href="mg-20160831.xsd#mg_BusinessCombinationProFormaInformationOperatingIncomeofAcquireesinceAcquisitionDateActual" xlink:label="loc_mg_BusinessCombinationProFormaInformationOperatingIncomeofAcquireesinceAcquisitionDateActual_EFDF4C418CF1DD35AE499D49452CABD6" xlink:type="locator" />
    <definitionArc order="9" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_E50059913E2F324904AC9D49452B7926" xlink:to="loc_mg_BusinessCombinationProFormaInformationOperatingIncomeofAcquireesinceAcquisitionDateActual_EFDF4C418CF1DD35AE499D49452CABD6" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://www.mistrasgroup.com/role/AcquisitionsPreliminaryPurchasePriceAllocationDetails" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_BusinessAcquisitionLineItems" xlink:label="loc_us-gaap_BusinessAcquisitionLineItems_72EB4065179A768884A49D4945253008" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable" xlink:label="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_BCE623432F4A415680C29D49452521BD" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_72EB4065179A768884A49D4945253008" xlink:to="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_BCE623432F4A415680C29D49452521BD" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_BusinessAcquisitionAxis" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_9FAD2A190AFD8543F5B49D49452573D4" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_BCE623432F4A415680C29D49452521BD" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_9FAD2A190AFD8543F5B49D49452573D4" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_E776930722D79638002A9D494525CEB4_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_9FAD2A190AFD8543F5B49D49452573D4" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_E776930722D79638002A9D494525CEB4_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_E776930722D79638002A9D494525CEB4" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_9FAD2A190AFD8543F5B49D49452573D4" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_E776930722D79638002A9D494525CEB4" xlink:type="arc" />
    <loc xlink:href="mg-20160831.xsd#mg_AcquisitionsinFiscal2017Member" xlink:label="loc_mg_AcquisitionsinFiscal2017Member_244607FA5EC250B3F6459D4945256841" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_E776930722D79638002A9D494525CEB4" xlink:to="loc_mg_AcquisitionsinFiscal2017Member_244607FA5EC250B3F6459D4945256841" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_StatementGeographicalAxis" xlink:label="loc_us-gaap_StatementGeographicalAxis_0601BF8AA0C1B481C1C99D4945255338" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_BCE623432F4A415680C29D49452521BD" xlink:to="loc_us-gaap_StatementGeographicalAxis_0601BF8AA0C1B481C1C99D4945255338" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_SegmentGeographicalDomain" xlink:label="loc_us-gaap_SegmentGeographicalDomain_89ACB2E7DE2126C333759D49452526D8_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementGeographicalAxis_0601BF8AA0C1B481C1C99D4945255338" xlink:to="loc_us-gaap_SegmentGeographicalDomain_89ACB2E7DE2126C333759D49452526D8_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_SegmentGeographicalDomain" xlink:label="loc_us-gaap_SegmentGeographicalDomain_89ACB2E7DE2126C333759D49452526D8" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementGeographicalAxis_0601BF8AA0C1B481C1C99D4945255338" xlink:to="loc_us-gaap_SegmentGeographicalDomain_89ACB2E7DE2126C333759D49452526D8" xlink:type="arc" />
    <loc xlink:href="http://xbrl.sec.gov/country/2013/country-2013-01-31.xsd#country_CA" xlink:label="loc_country_CA_A30B61239B9C3C9B58E69D494525A4DE" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentGeographicalDomain_89ACB2E7DE2126C333759D49452526D8" xlink:to="loc_country_CA_A30B61239B9C3C9B58E69D494525A4DE" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_NumberOfBusinessesAcquired" xlink:label="loc_us-gaap_NumberOfBusinessesAcquired_FC2EC03025DB0C053ADE9D4945251003" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_72EB4065179A768884A49D4945253008" xlink:to="loc_us-gaap_NumberOfBusinessesAcquired_FC2EC03025DB0C053ADE9D4945251003" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_PaymentsToAcquireBusinessesGross" xlink:label="loc_us-gaap_PaymentsToAcquireBusinessesGross_D69BDF827C03D12C1FF09D4945253C8C" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_72EB4065179A768884A49D4945253008" xlink:to="loc_us-gaap_PaymentsToAcquireBusinessesGross_D69BDF827C03D12C1FF09D4945253C8C" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_BusinessCombinationConsiderationTransferredLiabilitiesIncurred" xlink:label="loc_us-gaap_BusinessCombinationConsiderationTransferredLiabilitiesIncurred_13B3BB13B3136F948B769D565F1FD7FF" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_72EB4065179A768884A49D4945253008" xlink:to="loc_us-gaap_BusinessCombinationConsiderationTransferredLiabilitiesIncurred_13B3BB13B3136F948B769D565F1FD7FF" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_BusinessCombinationContingentConsiderationLiability" xlink:label="loc_us-gaap_BusinessCombinationContingentConsiderationLiability_7C839CFC1A69090B6A719D4945250072" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_72EB4065179A768884A49D4945253008" xlink:to="loc_us-gaap_BusinessCombinationContingentConsiderationLiability_7C839CFC1A69090B6A719D4945250072" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_BusinessCombinationConsiderationTransferred1" xlink:label="loc_us-gaap_BusinessCombinationConsiderationTransferred1_CF88B1302854E946C8CE9D49452643C0" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_72EB4065179A768884A49D4945253008" xlink:to="loc_us-gaap_BusinessCombinationConsiderationTransferred1_CF88B1302854E946C8CE9D49452643C0" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssets" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssets_2AA75464240DF4A7015B9D494526511F" xlink:type="locator" />
    <definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_72EB4065179A768884A49D4945253008" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssets_2AA75464240DF4A7015B9D494526511F" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPropertyPlantAndEquipment" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPropertyPlantAndEquipment_66CA4823E381262DED7B9D4945266442" xlink:type="locator" />
    <definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_72EB4065179A768884A49D4945253008" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPropertyPlantAndEquipment_66CA4823E381262DED7B9D4945266442" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibles" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibles_A8193125DB7B821CD2C69D494526E419" xlink:type="locator" />
    <definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_72EB4065179A768884A49D4945253008" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibles_A8193125DB7B821CD2C69D494526E419" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_Goodwill" xlink:label="loc_us-gaap_Goodwill_C3322E6493947AF5389B9D494526700A" xlink:type="locator" />
    <definitionArc order="9" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_72EB4065179A768884A49D4945253008" xlink:to="loc_us-gaap_Goodwill_C3322E6493947AF5389B9D494526700A" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilities" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilities_30715CE9DE53F817A3FA9D494526EF5E" xlink:type="locator" />
    <definitionArc order="10" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_72EB4065179A768884A49D4945253008" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilities_30715CE9DE53F817A3FA9D494526EF5E" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedDeferredTaxLiabilitiesNoncurrent" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedDeferredTaxLiabilitiesNoncurrent_464DB0CD7B6FCB75A2C29D49452606D5" xlink:type="locator" />
    <definitionArc order="11" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_72EB4065179A768884A49D4945253008" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedDeferredTaxLiabilitiesNoncurrent_464DB0CD7B6FCB75A2C29D49452606D5" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet_DF45D6DA71997E952DCB9D49452600F0" xlink:type="locator" />
    <definitionArc order="12" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_72EB4065179A768884A49D4945253008" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet_DF45D6DA71997E952DCB9D49452600F0" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://www.mistrasgroup.com/role/AcquisitionsTables" xlink:type="extended" />
  <definitionLink xlink:role="http://www.mistrasgroup.com/role/CommitmentsAndContingencies" xlink:type="extended" />
  <definitionLink xlink:role="http://www.mistrasgroup.com/role/CommitmentsAndContingenciesDetails" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LossContingenciesLineItems" xlink:label="loc_us-gaap_LossContingenciesLineItems_678A3DBE86510DF2FA509D494411D93C" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LossContingenciesTable" xlink:label="loc_us-gaap_LossContingenciesTable_48EF3DE38060A5E484CD9D494410F565" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LossContingenciesLineItems_678A3DBE86510DF2FA509D494411D93C" xlink:to="loc_us-gaap_LossContingenciesTable_48EF3DE38060A5E484CD9D494410F565" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_RelatedPartyTransactionsByRelatedPartyAxis" xlink:label="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_277C5EAC18154D15D50B9D4944104E21" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_48EF3DE38060A5E484CD9D494410F565" xlink:to="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_277C5EAC18154D15D50B9D4944104E21" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_RelatedPartyDomain" xlink:label="loc_us-gaap_RelatedPartyDomain_50249DDC45358FD937AA9D494410A733_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_277C5EAC18154D15D50B9D4944104E21" xlink:to="loc_us-gaap_RelatedPartyDomain_50249DDC45358FD937AA9D494410A733_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_RelatedPartyDomain" xlink:label="loc_us-gaap_RelatedPartyDomain_50249DDC45358FD937AA9D494410A733" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_277C5EAC18154D15D50B9D4944104E21" xlink:to="loc_us-gaap_RelatedPartyDomain_50249DDC45358FD937AA9D494410A733" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AffiliatedEntityMember" xlink:label="loc_us-gaap_AffiliatedEntityMember_1B2E953465EFDEE0CF4F9D494410C79C" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyDomain_50249DDC45358FD937AA9D494410A733" xlink:to="loc_us-gaap_AffiliatedEntityMember_1B2E953465EFDEE0CF4F9D494410C79C" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LossContingenciesByNatureOfContingencyAxis" xlink:label="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_34188202CF4BFCC064AC9D4944106E54" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_48EF3DE38060A5E484CD9D494410F565" xlink:to="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_34188202CF4BFCC064AC9D4944106E54" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LossContingencyNatureDomain" xlink:label="loc_us-gaap_LossContingencyNatureDomain_FBC8749259D7B0B477669D49441140CF_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_34188202CF4BFCC064AC9D4944106E54" xlink:to="loc_us-gaap_LossContingencyNatureDomain_FBC8749259D7B0B477669D49441140CF_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LossContingencyNatureDomain" xlink:label="loc_us-gaap_LossContingencyNatureDomain_FBC8749259D7B0B477669D49441140CF" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_34188202CF4BFCC064AC9D4944106E54" xlink:to="loc_us-gaap_LossContingencyNatureDomain_FBC8749259D7B0B477669D49441140CF" xlink:type="arc" />
    <loc xlink:href="mg-20160831.xsd#mg_ConsolidatedclassandcollectiveactionlawsuitMember" xlink:label="loc_mg_ConsolidatedclassandcollectiveactionlawsuitMember_6473277A6B085BD020789D494411FC80" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingencyNatureDomain_FBC8749259D7B0B477669D49441140CF" xlink:to="loc_mg_ConsolidatedclassandcollectiveactionlawsuitMember_6473277A6B085BD020789D494411FC80" xlink:type="arc" />
    <loc xlink:href="mg-20160831.xsd#mg_LawsuitForDamagesResultingFromAllegedQualityDefectsMember" xlink:label="loc_mg_LawsuitForDamagesResultingFromAllegedQualityDefectsMember_5BF3F03A43C2260ED7789D49441156BE" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingencyNatureDomain_FBC8749259D7B0B477669D49441140CF" xlink:to="loc_mg_LawsuitForDamagesResultingFromAllegedQualityDefectsMember_5BF3F03A43C2260ED7789D49441156BE" xlink:type="arc" />
    <loc xlink:href="mg-20160831.xsd#mg_DisputewithformerownerofcompanysFrenchsubsidiaryMember" xlink:label="loc_mg_DisputewithformerownerofcompanysFrenchsubsidiaryMember_E68459B1DA8B8762983C9D494411B85E" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingencyNatureDomain_FBC8749259D7B0B477669D49441140CF" xlink:to="loc_mg_DisputewithformerownerofcompanysFrenchsubsidiaryMember_E68459B1DA8B8762983C9D494411B85E" xlink:type="arc" />
    <loc xlink:href="mg-20160831.xsd#mg_AcquisitionRelatedContingenciesMember" xlink:label="loc_mg_AcquisitionRelatedContingenciesMember_C11BC3E49030587C520B9D494411CA2A" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingencyNatureDomain_FBC8749259D7B0B477669D49441140CF" xlink:to="loc_mg_AcquisitionRelatedContingenciesMember_C11BC3E49030587C520B9D494411CA2A" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LitigationSettlementAmount" xlink:label="loc_us-gaap_LitigationSettlementAmount_F305F9902AED02E741EA9D4944110518" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_678A3DBE86510DF2FA509D494411D93C" xlink:to="loc_us-gaap_LitigationSettlementAmount_F305F9902AED02E741EA9D4944110518" xlink:type="arc" />
    <loc xlink:href="mg-20160831.xsd#mg_LitigationSettlementAmountincludingExpense" xlink:label="loc_mg_LitigationSettlementAmountincludingExpense_EB0869D8C09024BAF8439D4944113027" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_678A3DBE86510DF2FA509D494411D93C" xlink:to="loc_mg_LitigationSettlementAmountincludingExpense_EB0869D8C09024BAF8439D4944113027" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LossContingencyNumberOfPlaintiffs" xlink:label="loc_us-gaap_LossContingencyNumberOfPlaintiffs_356B5A3C1C6F1F78E0869D494412E04C" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_678A3DBE86510DF2FA509D494411D93C" xlink:to="loc_us-gaap_LossContingencyNumberOfPlaintiffs_356B5A3C1C6F1F78E0869D494412E04C" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LossContingencyNewClaimsFiledNumber" xlink:label="loc_us-gaap_LossContingencyNewClaimsFiledNumber_AC717F80148F24C75E059D494412F51B" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_678A3DBE86510DF2FA509D494411D93C" xlink:to="loc_us-gaap_LossContingencyNewClaimsFiledNumber_AC717F80148F24C75E059D494412F51B" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LossContingencyDamagesSoughtValue" xlink:label="loc_us-gaap_LossContingencyDamagesSoughtValue_112CC84915FD50BB54839D49441208F2" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_678A3DBE86510DF2FA509D494411D93C" xlink:to="loc_us-gaap_LossContingencyDamagesSoughtValue_112CC84915FD50BB54839D49441208F2" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_BusinessCombinationContingentConsiderationArrangementsRangeOfOutcomesValueLow" xlink:label="loc_us-gaap_BusinessCombinationContingentConsiderationArrangementsRangeOfOutcomesValueLow_1752F7C53CCD5A2C7FA59D4944126DB4" xlink:type="locator" />
    <definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_678A3DBE86510DF2FA509D494411D93C" xlink:to="loc_us-gaap_BusinessCombinationContingentConsiderationArrangementsRangeOfOutcomesValueLow_1752F7C53CCD5A2C7FA59D4944126DB4" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_BusinessCombinationContingentConsiderationArrangementsRangeOfOutcomesValueHigh" xlink:label="loc_us-gaap_BusinessCombinationContingentConsiderationArrangementsRangeOfOutcomesValueHigh_36C6A4B8F4DDE70889249D494412A909" xlink:type="locator" />
    <definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_678A3DBE86510DF2FA509D494411D93C" xlink:to="loc_us-gaap_BusinessCombinationContingentConsiderationArrangementsRangeOfOutcomesValueHigh_36C6A4B8F4DDE70889249D494412A909" xlink:type="arc" />
    <loc xlink:href="mg-20160831.xsd#mg_BusinessCombinationContingentConsiderationPaymentPeriod" xlink:label="loc_mg_BusinessCombinationContingentConsiderationPaymentPeriod_425F8B6FB2E07409FF679D494412E98F" xlink:type="locator" />
    <definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_678A3DBE86510DF2FA509D494411D93C" xlink:to="loc_mg_BusinessCombinationContingentConsiderationPaymentPeriod_425F8B6FB2E07409FF679D494412E98F" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://www.mistrasgroup.com/role/CondensedConsolidatedBalanceSheets" xlink:type="extended" />
  <definitionLink xlink:role="http://www.mistrasgroup.com/role/CondensedConsolidatedBalanceSheetsParenthetical" xlink:type="extended" />
  <definitionLink xlink:role="http://www.mistrasgroup.com/role/DescriptionOfBusinessandBasisOfPresentation" xlink:type="extended" />
  <definitionLink xlink:role="http://www.mistrasgroup.com/role/DescriptionOfBusinessandBasisOfPresentationAdditionalInformationDetails" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ConcentrationRiskLineItems" xlink:label="loc_us-gaap_ConcentrationRiskLineItems_09327DFB66B5105677639195B1B06747" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ConcentrationRiskTable" xlink:label="loc_us-gaap_ConcentrationRiskTable_F762E3BD05D89BF8D51C9195B1B036A2" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_09327DFB66B5105677639195B1B06747" xlink:to="loc_us-gaap_ConcentrationRiskTable_F762E3BD05D89BF8D51C9195B1B036A2" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ConcentrationRiskByTypeAxis" xlink:label="loc_us-gaap_ConcentrationRiskByTypeAxis_23E8F3CC1B78D8C0B2B6919651BFFD0B" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ConcentrationRiskTable_F762E3BD05D89BF8D51C9195B1B036A2" xlink:to="loc_us-gaap_ConcentrationRiskByTypeAxis_23E8F3CC1B78D8C0B2B6919651BFFD0B" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ConcentrationRiskTypeDomain" xlink:label="loc_us-gaap_ConcentrationRiskTypeDomain_6E42DBF8FB69F84295A0919653100D1D_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConcentrationRiskByTypeAxis_23E8F3CC1B78D8C0B2B6919651BFFD0B" xlink:to="loc_us-gaap_ConcentrationRiskTypeDomain_6E42DBF8FB69F84295A0919653100D1D_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ConcentrationRiskTypeDomain" xlink:label="loc_us-gaap_ConcentrationRiskTypeDomain_6E42DBF8FB69F84295A0919653100D1D" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConcentrationRiskByTypeAxis_23E8F3CC1B78D8C0B2B6919651BFFD0B" xlink:to="loc_us-gaap_ConcentrationRiskTypeDomain_6E42DBF8FB69F84295A0919653100D1D" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_CustomerConcentrationRiskMember" xlink:label="loc_us-gaap_CustomerConcentrationRiskMember_48C4E30B5DFD6151E5DC919651DE3DE2" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskTypeDomain_6E42DBF8FB69F84295A0919653100D1D" xlink:to="loc_us-gaap_CustomerConcentrationRiskMember_48C4E30B5DFD6151E5DC919651DE3DE2" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ConcentrationRiskByBenchmarkAxis" xlink:label="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_66167588A9DDF9D29947919651D0D4B2" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ConcentrationRiskTable_F762E3BD05D89BF8D51C9195B1B036A2" xlink:to="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_66167588A9DDF9D29947919651D0D4B2" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ConcentrationRiskBenchmarkDomain" xlink:label="loc_us-gaap_ConcentrationRiskBenchmarkDomain_88C93ADE6E9862EAC7579196531EC195_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_66167588A9DDF9D29947919651D0D4B2" xlink:to="loc_us-gaap_ConcentrationRiskBenchmarkDomain_88C93ADE6E9862EAC7579196531EC195_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ConcentrationRiskBenchmarkDomain" xlink:label="loc_us-gaap_ConcentrationRiskBenchmarkDomain_88C93ADE6E9862EAC7579196531EC195" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_66167588A9DDF9D29947919651D0D4B2" xlink:to="loc_us-gaap_ConcentrationRiskBenchmarkDomain_88C93ADE6E9862EAC7579196531EC195" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_SalesRevenueNetMember" xlink:label="loc_us-gaap_SalesRevenueNetMember_92AF854F3F0DFB945F9C919651EEBF8D" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskBenchmarkDomain_88C93ADE6E9862EAC7579196531EC195" xlink:to="loc_us-gaap_SalesRevenueNetMember_92AF854F3F0DFB945F9C919651EEBF8D" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AccountsReceivableMember" xlink:label="loc_us-gaap_AccountsReceivableMember_21ECE14C358BADF1C95B919651FB9279" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskBenchmarkDomain_88C93ADE6E9862EAC7579196531EC195" xlink:to="loc_us-gaap_AccountsReceivableMember_21ECE14C358BADF1C95B919651FB9279" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_StatementBusinessSegmentsAxis" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_57B10307D2D433A0FAE2919D2A70167D" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ConcentrationRiskTable_F762E3BD05D89BF8D51C9195B1B036A2" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_57B10307D2D433A0FAE2919D2A70167D" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_SegmentDomain" xlink:label="loc_us-gaap_SegmentDomain_19E0F2E7F51D9BC9DA15919D2A702CB9_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_57B10307D2D433A0FAE2919D2A70167D" xlink:to="loc_us-gaap_SegmentDomain_19E0F2E7F51D9BC9DA15919D2A702CB9_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_SegmentDomain" xlink:label="loc_us-gaap_SegmentDomain_19E0F2E7F51D9BC9DA15919D2A702CB9" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_57B10307D2D433A0FAE2919D2A70167D" xlink:to="loc_us-gaap_SegmentDomain_19E0F2E7F51D9BC9DA15919D2A702CB9" xlink:type="arc" />
    <loc xlink:href="mg-20160831.xsd#mg_ServicesMember" xlink:label="loc_mg_ServicesMember_94C84677FECE82D3CAC5919D54F6243F" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_19E0F2E7F51D9BC9DA15919D2A702CB9" xlink:to="loc_mg_ServicesMember_94C84677FECE82D3CAC5919D54F6243F" xlink:type="arc" />
    <loc xlink:href="mg-20160831.xsd#mg_ConcentrationRiskNumberOfCustomers" xlink:label="loc_mg_ConcentrationRiskNumberOfCustomers_F318384B7BE5CF0B0856919F74722E2C" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_09327DFB66B5105677639195B1B06747" xlink:to="loc_mg_ConcentrationRiskNumberOfCustomers_F318384B7BE5CF0B0856919F74722E2C" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ConcentrationRiskPercentage1" xlink:label="loc_us-gaap_ConcentrationRiskPercentage1_EFCF77DAE16ACE69EEB9919651B23C5E" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_09327DFB66B5105677639195B1B06747" xlink:to="loc_us-gaap_ConcentrationRiskPercentage1_EFCF77DAE16ACE69EEB9919651B23C5E" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://www.mistrasgroup.com/role/DescriptionOfBusinessandBasisOfPresentationPolicies" xlink:type="extended" />
  <definitionLink xlink:role="http://www.mistrasgroup.com/role/DocumentAndEntityInformation" xlink:type="extended" />
  <definitionLink xlink:role="http://www.mistrasgroup.com/role/EarningsPerShare" xlink:type="extended" />
  <definitionLink xlink:role="http://www.mistrasgroup.com/role/EarningsPerShareDetails" xlink:type="extended" />
  <definitionLink xlink:role="http://www.mistrasgroup.com/role/EarningsPerShareTables" xlink:type="extended" />
  <definitionLink xlink:role="http://www.mistrasgroup.com/role/FairValueMeasurements" xlink:type="extended" />
  <definitionLink xlink:role="http://www.mistrasgroup.com/role/FairValueMeasurementsDetails" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_8874D51472CE5C13B462677DFD5BC529" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_5419EF164D1F526481730D8F154009F2" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_8874D51472CE5C13B462677DFD5BC529" xlink:to="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_5419EF164D1F526481730D8F154009F2" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FairValueByMeasurementFrequencyAxis" xlink:label="loc_us-gaap_FairValueByMeasurementFrequencyAxis_61022B3E1E1F5AE9BB847861858E24B2" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_5419EF164D1F526481730D8F154009F2" xlink:to="loc_us-gaap_FairValueByMeasurementFrequencyAxis_61022B3E1E1F5AE9BB847861858E24B2" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FairValueMeasurementFrequencyDomain" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_416E901123F28832768CBF784AF0F77B_414638B1748D5388A78ACB92B5341A8F" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_61022B3E1E1F5AE9BB847861858E24B2" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_416E901123F28832768CBF784AF0F77B_414638B1748D5388A78ACB92B5341A8F" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FairValueMeasurementFrequencyDomain" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_EB04FE5124BB5AB6972B568B7211B4E3" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_61022B3E1E1F5AE9BB847861858E24B2" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_EB04FE5124BB5AB6972B568B7211B4E3" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FairValueMeasurementsRecurringMember" xlink:label="loc_us-gaap_FairValueMeasurementsRecurringMember_20C3F329FA2351BA95FE2CE297BB47AB" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementFrequencyDomain_EB04FE5124BB5AB6972B568B7211B4E3" xlink:to="loc_us-gaap_FairValueMeasurementsRecurringMember_20C3F329FA2351BA95FE2CE297BB47AB" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_6F8233FB5A8C5EE7BA9F83DE855CBCE4" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_5419EF164D1F526481730D8F154009F2" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_6F8233FB5A8C5EE7BA9F83DE855CBCE4" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_E93092CE6A2586F3345EBF784AF10690_414638B1748D5388A78ACB92B5341A8F" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_6F8233FB5A8C5EE7BA9F83DE855CBCE4" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_E93092CE6A2586F3345EBF784AF10690_414638B1748D5388A78ACB92B5341A8F" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_3471824180C85E80893B34BD72C8BA24" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_6F8233FB5A8C5EE7BA9F83DE855CBCE4" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_3471824180C85E80893B34BD72C8BA24" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FairValueInputsLevel1Member" xlink:label="loc_us-gaap_FairValueInputsLevel1Member_DDE62FB3134C52E39CD4187F0AB8AF28" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_3471824180C85E80893B34BD72C8BA24" xlink:to="loc_us-gaap_FairValueInputsLevel1Member_DDE62FB3134C52E39CD4187F0AB8AF28" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FairValueInputsLevel2Member" xlink:label="loc_us-gaap_FairValueInputsLevel2Member_6F1DDC6E70C6575DBE43A187C600735D" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_3471824180C85E80893B34BD72C8BA24" xlink:to="loc_us-gaap_FairValueInputsLevel2Member_6F1DDC6E70C6575DBE43A187C600735D" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FairValueInputsLevel3Member" xlink:label="loc_us-gaap_FairValueInputsLevel3Member_E450FE232DF25ED3B6E5A70CA7C8F609" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_3471824180C85E80893B34BD72C8BA24" xlink:to="loc_us-gaap_FairValueInputsLevel3Member_E450FE232DF25ED3B6E5A70CA7C8F609" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LiabilitiesFairValueDisclosureAbstract" xlink:label="loc_us-gaap_LiabilitiesFairValueDisclosureAbstract_EB31D97DACE15784B0A6B0EA2A53F2C3" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_8874D51472CE5C13B462677DFD5BC529" xlink:to="loc_us-gaap_LiabilitiesFairValueDisclosureAbstract_EB31D97DACE15784B0A6B0EA2A53F2C3" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_BusinessCombinationContingentConsiderationLiability" xlink:label="loc_us-gaap_BusinessCombinationContingentConsiderationLiability_D344F108B4C85072967C68A4566A5EB6" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesFairValueDisclosureAbstract_EB31D97DACE15784B0A6B0EA2A53F2C3" xlink:to="loc_us-gaap_BusinessCombinationContingentConsiderationLiability_D344F108B4C85072967C68A4566A5EB6" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LiabilitiesFairValueDisclosure" xlink:label="loc_us-gaap_LiabilitiesFairValueDisclosure_EC234CC0117852CF90180A89898FD8E9" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesFairValueDisclosureAbstract_EB31D97DACE15784B0A6B0EA2A53F2C3" xlink:to="loc_us-gaap_LiabilitiesFairValueDisclosure_EC234CC0117852CF90180A89898FD8E9" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://www.mistrasgroup.com/role/FairValueMeasurementsTables" xlink:type="extended" />
  <definitionLink xlink:role="http://www.mistrasgroup.com/role/Goodwill" xlink:type="extended" />
  <definitionLink xlink:role="http://www.mistrasgroup.com/role/GoodwillDetails" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_GoodwillLineItems" xlink:label="loc_us-gaap_GoodwillLineItems_9417C6C6E7B7D167DAA39B3BDAFFC6E3" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ScheduleOfGoodwillTable" xlink:label="loc_us-gaap_ScheduleOfGoodwillTable_0C5DE1B8B51C8FCEC2A79B3BDAFF679F" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_GoodwillLineItems_9417C6C6E7B7D167DAA39B3BDAFFC6E3" xlink:to="loc_us-gaap_ScheduleOfGoodwillTable_0C5DE1B8B51C8FCEC2A79B3BDAFF679F" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_StatementBusinessSegmentsAxis" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_2D215A9C5C3B8A4DD6899B3BDAFFEB1D" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfGoodwillTable_0C5DE1B8B51C8FCEC2A79B3BDAFF679F" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_2D215A9C5C3B8A4DD6899B3BDAFFEB1D" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_SegmentDomain" xlink:label="loc_us-gaap_SegmentDomain_0114F26455B7FDFD0D819B3BDAFF9632_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_2D215A9C5C3B8A4DD6899B3BDAFFEB1D" xlink:to="loc_us-gaap_SegmentDomain_0114F26455B7FDFD0D819B3BDAFF9632_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_SegmentDomain" xlink:label="loc_us-gaap_SegmentDomain_0114F26455B7FDFD0D819B3BDAFF9632" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_2D215A9C5C3B8A4DD6899B3BDAFFEB1D" xlink:to="loc_us-gaap_SegmentDomain_0114F26455B7FDFD0D819B3BDAFF9632" xlink:type="arc" />
    <loc xlink:href="mg-20160831.xsd#mg_ServicesMember" xlink:label="loc_mg_ServicesMember_D3A7FA57D26CB41AA4E59B3BDAFFB443" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_0114F26455B7FDFD0D819B3BDAFF9632" xlink:to="loc_mg_ServicesMember_D3A7FA57D26CB41AA4E59B3BDAFFB443" xlink:type="arc" />
    <loc xlink:href="mg-20160831.xsd#mg_InternationalMember" xlink:label="loc_mg_InternationalMember_65AF2E5FBAFBFDEF59579B3BDAFF0604" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_0114F26455B7FDFD0D819B3BDAFF9632" xlink:to="loc_mg_InternationalMember_65AF2E5FBAFBFDEF59579B3BDAFF0604" xlink:type="arc" />
    <loc xlink:href="mg-20160831.xsd#mg_ProductsAndSystemsMember" xlink:label="loc_mg_ProductsAndSystemsMember_C3C0A00B20EB7D6825BB9B3BDAFFA6CF" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_0114F26455B7FDFD0D819B3BDAFF9632" xlink:to="loc_mg_ProductsAndSystemsMember_C3C0A00B20EB7D6825BB9B3BDAFFA6CF" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_GoodwillRollForward" xlink:label="loc_us-gaap_GoodwillRollForward_E26C93F09A1522F979E89B3BDAFF2E4A" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillLineItems_9417C6C6E7B7D167DAA39B3BDAFFC6E3" xlink:to="loc_us-gaap_GoodwillRollForward_E26C93F09A1522F979E89B3BDAFF2E4A" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_Goodwill" xlink:label="loc_us-gaap_Goodwill_BDC1C39598207E5F2AE59B3BDAFFC1CA" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillRollForward_E26C93F09A1522F979E89B3BDAFF2E4A" xlink:to="loc_us-gaap_Goodwill_BDC1C39598207E5F2AE59B3BDAFFC1CA" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_GoodwillPeriodIncreaseDecrease" xlink:label="loc_us-gaap_GoodwillPeriodIncreaseDecrease_DCB5A683D029D2B26BAD9B50E9D3F854" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillRollForward_E26C93F09A1522F979E89B3BDAFF2E4A" xlink:to="loc_us-gaap_GoodwillPeriodIncreaseDecrease_DCB5A683D029D2B26BAD9B50E9D3F854" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_GoodwillPurchaseAccountingAdjustments" xlink:label="loc_us-gaap_GoodwillPurchaseAccountingAdjustments_AB408ADCC1E822B1C01C9B3BDAFFF8A3" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillRollForward_E26C93F09A1522F979E89B3BDAFF2E4A" xlink:to="loc_us-gaap_GoodwillPurchaseAccountingAdjustments_AB408ADCC1E822B1C01C9B3BDAFFF8A3" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_GoodwillTranslationAdjustments" xlink:label="loc_us-gaap_GoodwillTranslationAdjustments_69FF365477E8D33FDCBD9B3BDB0093B7" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillRollForward_E26C93F09A1522F979E89B3BDAFF2E4A" xlink:to="loc_us-gaap_GoodwillTranslationAdjustments_69FF365477E8D33FDCBD9B3BDB0093B7" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_GoodwillImpairedAccumulatedImpairmentLoss" xlink:label="loc_us-gaap_GoodwillImpairedAccumulatedImpairmentLoss_7F0BA1B73D884E8447779B3BDAFFE758" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillLineItems_9417C6C6E7B7D167DAA39B3BDAFFC6E3" xlink:to="loc_us-gaap_GoodwillImpairedAccumulatedImpairmentLoss_7F0BA1B73D884E8447779B3BDAFFE758" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://www.mistrasgroup.com/role/GoodwillTables" xlink:type="extended" />
  <definitionLink xlink:role="http://www.mistrasgroup.com/role/IntangibleAssets" xlink:type="extended" />
  <definitionLink xlink:role="http://www.mistrasgroup.com/role/IntangibleAssetsDetails" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsLineItems" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_116A94896C875033BE1366EA2B3F197B" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable" xlink:label="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_FB326B53EA6152A2991DCC449D885F4F" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_116A94896C875033BE1366EA2B3F197B" xlink:to="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_FB326B53EA6152A2991DCC449D885F4F" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_85BD93BA6D1E5A7592F20781CEF23775" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_FB326B53EA6152A2991DCC449D885F4F" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_85BD93BA6D1E5A7592F20781CEF23775" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_0799E6D4235B81A18AF2B0CA6028185C_DDC566A23FC25E7A9D2A883A037C0F6B" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_85BD93BA6D1E5A7592F20781CEF23775" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_0799E6D4235B81A18AF2B0CA6028185C_DDC566A23FC25E7A9D2A883A037C0F6B" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_2EE48E6BB6155C45ABB6A5CAFD455EFB" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_85BD93BA6D1E5A7592F20781CEF23775" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_2EE48E6BB6155C45ABB6A5CAFD455EFB" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_CustomerRelationshipsMember" xlink:label="loc_us-gaap_CustomerRelationshipsMember_D178B1E9223B5BC7AF567A0DC31F1F71" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_2EE48E6BB6155C45ABB6A5CAFD455EFB" xlink:to="loc_us-gaap_CustomerRelationshipsMember_D178B1E9223B5BC7AF567A0DC31F1F71" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ComputerSoftwareIntangibleAssetMember" xlink:label="loc_us-gaap_ComputerSoftwareIntangibleAssetMember_44582F275BC05045A9255041E7BA419C" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_2EE48E6BB6155C45ABB6A5CAFD455EFB" xlink:to="loc_us-gaap_ComputerSoftwareIntangibleAssetMember_44582F275BC05045A9255041E7BA419C" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_NoncompeteAgreementsMember" xlink:label="loc_us-gaap_NoncompeteAgreementsMember_E639E773871A5E638CAEF0442641C1D2" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_2EE48E6BB6155C45ABB6A5CAFD455EFB" xlink:to="loc_us-gaap_NoncompeteAgreementsMember_E639E773871A5E638CAEF0442641C1D2" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_OtherIntangibleAssetsMember" xlink:label="loc_us-gaap_OtherIntangibleAssetsMember_EC604ED4FCEB50DEBA7D81DE85666F2B" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_2EE48E6BB6155C45ABB6A5CAFD455EFB" xlink:to="loc_us-gaap_OtherIntangibleAssetsMember_EC604ED4FCEB50DEBA7D81DE85666F2B" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_RangeAxis" xlink:label="loc_us-gaap_RangeAxis_6092C99D72515BABA398293FEFF358FC" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_FB326B53EA6152A2991DCC449D885F4F" xlink:to="loc_us-gaap_RangeAxis_6092C99D72515BABA398293FEFF358FC" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_RangeMember" xlink:label="loc_us-gaap_RangeMember_6F6F864996ECF8F957ABB0CA6029AAA0_DDC566A23FC25E7A9D2A883A037C0F6B" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RangeAxis_6092C99D72515BABA398293FEFF358FC" xlink:to="loc_us-gaap_RangeMember_6F6F864996ECF8F957ABB0CA6029AAA0_DDC566A23FC25E7A9D2A883A037C0F6B" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_RangeMember" xlink:label="loc_us-gaap_RangeMember_50C1AF8608E85BA8A6EC44D7CD4AC49E" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RangeAxis_6092C99D72515BABA398293FEFF358FC" xlink:to="loc_us-gaap_RangeMember_50C1AF8608E85BA8A6EC44D7CD4AC49E" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_MinimumMember" xlink:label="loc_us-gaap_MinimumMember_5A356F1260E45A099E1B674030D93669" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RangeMember_50C1AF8608E85BA8A6EC44D7CD4AC49E" xlink:to="loc_us-gaap_MinimumMember_5A356F1260E45A099E1B674030D93669" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_MaximumMember" xlink:label="loc_us-gaap_MaximumMember_211FE67F5D6C5D1D8824B519121C5D95" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RangeMember_50C1AF8608E85BA8A6EC44D7CD4AC49E" xlink:to="loc_us-gaap_MaximumMember_211FE67F5D6C5D1D8824B519121C5D95" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetUsefulLife" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetUsefulLife_D407758EA37E50348A367C61D15AA5BD" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_116A94896C875033BE1366EA2B3F197B" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetUsefulLife_D407758EA37E50348A367C61D15AA5BD" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsGross" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsGross_1B2C4190493B5A4FB82323CF264AA017" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_116A94896C875033BE1366EA2B3F197B" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsGross_1B2C4190493B5A4FB82323CF264AA017" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_CAC335D21E88556B903D72DAA3193EE5" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_116A94896C875033BE1366EA2B3F197B" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_CAC335D21E88556B903D72DAA3193EE5" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_IntangibleAssetsNetExcludingGoodwill" xlink:label="loc_us-gaap_IntangibleAssetsNetExcludingGoodwill_55A6AC0C0BCB5C4DB3C26ECC5BC149CA" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_116A94896C875033BE1366EA2B3F197B" xlink:to="loc_us-gaap_IntangibleAssetsNetExcludingGoodwill_55A6AC0C0BCB5C4DB3C26ECC5BC149CA" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://www.mistrasgroup.com/role/IntangibleAssetsTables" xlink:type="extended" />
  <definitionLink xlink:role="http://www.mistrasgroup.com/role/LongTermDebt" xlink:type="extended" />
  <definitionLink xlink:role="http://www.mistrasgroup.com/role/LongTermDebtAdditionalInformationDetails" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DebtInstrumentLineItems" xlink:label="loc_us-gaap_DebtInstrumentLineItems_0BE20ADEF0058DBB704676C22A55D171" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DebtInstrumentTable" xlink:label="loc_us-gaap_DebtInstrumentTable_93063C01AA7A8084458676C22A5477B2" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_0BE20ADEF0058DBB704676C22A55D171" xlink:to="loc_us-gaap_DebtInstrumentTable_93063C01AA7A8084458676C22A5477B2" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LongtermDebtTypeAxis" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_0D603572C629278CF67376C22A54B267" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_93063C01AA7A8084458676C22A5477B2" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_0D603572C629278CF67376C22A54B267" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LongtermDebtTypeDomain" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_864E94DA03B580996F7D76C22A5473D7_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_0D603572C629278CF67376C22A54B267" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_864E94DA03B580996F7D76C22A5473D7_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LongtermDebtTypeDomain" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_864E94DA03B580996F7D76C22A5473D7" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_0D603572C629278CF67376C22A54B267" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_864E94DA03B580996F7D76C22A5473D7" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_RevolvingCreditFacilityMember" xlink:label="loc_us-gaap_RevolvingCreditFacilityMember_8DD178112013BB163B3776C22A54F3C8" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_864E94DA03B580996F7D76C22A5473D7" xlink:to="loc_us-gaap_RevolvingCreditFacilityMember_8DD178112013BB163B3776C22A54F3C8" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_NotesPayableOtherPayablesMember" xlink:label="loc_us-gaap_NotesPayableOtherPayablesMember_B8140AFC66E7444227C976C22A54035D" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_864E94DA03B580996F7D76C22A5473D7" xlink:to="loc_us-gaap_NotesPayableOtherPayablesMember_B8140AFC66E7444227C976C22A54035D" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_VariableRateAxis" xlink:label="loc_us-gaap_VariableRateAxis_105D1BEED192E59404A476C22A54D1A1" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_93063C01AA7A8084458676C22A5477B2" xlink:to="loc_us-gaap_VariableRateAxis_105D1BEED192E59404A476C22A54D1A1" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_VariableRateDomain" xlink:label="loc_us-gaap_VariableRateDomain_C7C0766BC3C87277908B76C22A543376_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_VariableRateAxis_105D1BEED192E59404A476C22A54D1A1" xlink:to="loc_us-gaap_VariableRateDomain_C7C0766BC3C87277908B76C22A543376_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_VariableRateDomain" xlink:label="loc_us-gaap_VariableRateDomain_C7C0766BC3C87277908B76C22A543376" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_VariableRateAxis_105D1BEED192E59404A476C22A54D1A1" xlink:to="loc_us-gaap_VariableRateDomain_C7C0766BC3C87277908B76C22A543376" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LondonInterbankOfferedRateLIBORMember" xlink:label="loc_us-gaap_LondonInterbankOfferedRateLIBORMember_3865777E7B41FDBF333876C22A546CC3" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableRateDomain_C7C0766BC3C87277908B76C22A543376" xlink:to="loc_us-gaap_LondonInterbankOfferedRateLIBORMember_3865777E7B41FDBF333876C22A546CC3" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_BaseRateMember" xlink:label="loc_us-gaap_BaseRateMember_148AD1A980C9DE9C9BD176C22A5409C4" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableRateDomain_C7C0766BC3C87277908B76C22A543376" xlink:to="loc_us-gaap_BaseRateMember_148AD1A980C9DE9C9BD176C22A5409C4" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_RangeAxis" xlink:label="loc_us-gaap_RangeAxis_530C6C090E2EB168C51176C22A548FD2" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_93063C01AA7A8084458676C22A5477B2" xlink:to="loc_us-gaap_RangeAxis_530C6C090E2EB168C51176C22A548FD2" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_RangeMember" xlink:label="loc_us-gaap_RangeMember_96962B64438C0F672E8B76C22A549CD1_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RangeAxis_530C6C090E2EB168C51176C22A548FD2" xlink:to="loc_us-gaap_RangeMember_96962B64438C0F672E8B76C22A549CD1_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_RangeMember" xlink:label="loc_us-gaap_RangeMember_96962B64438C0F672E8B76C22A549CD1" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RangeAxis_530C6C090E2EB168C51176C22A548FD2" xlink:to="loc_us-gaap_RangeMember_96962B64438C0F672E8B76C22A549CD1" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_MinimumMember" xlink:label="loc_us-gaap_MinimumMember_6EBC13B77A06C9A3EC9276C22A55135F" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RangeMember_96962B64438C0F672E8B76C22A549CD1" xlink:to="loc_us-gaap_MinimumMember_6EBC13B77A06C9A3EC9276C22A55135F" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_MaximumMember" xlink:label="loc_us-gaap_MaximumMember_5B150618B011626B9D8B76C22A5532F8" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RangeMember_96962B64438C0F672E8B76C22A549CD1" xlink:to="loc_us-gaap_MaximumMember_5B150618B011626B9D8B76C22A5532F8" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LineOfCreditFacilityAbstract" xlink:label="loc_us-gaap_LineOfCreditFacilityAbstract_6B5EBE6F193B5ED53C2476C22A5A8CD5" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_0BE20ADEF0058DBB704676C22A55D171" xlink:to="loc_us-gaap_LineOfCreditFacilityAbstract_6B5EBE6F193B5ED53C2476C22A5A8CD5" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity" xlink:label="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_AED5E781FD030EAFAE6476C22A5AF9C5" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityAbstract_6B5EBE6F193B5ED53C2476C22A5A8CD5" xlink:to="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_AED5E781FD030EAFAE6476C22A5AF9C5" xlink:type="arc" />
    <loc xlink:href="mg-20160831.xsd#mg_LineOfCreditFacilityAccordionFeatureHigherBorrowingCapacityOption" xlink:label="loc_mg_LineOfCreditFacilityAccordionFeatureHigherBorrowingCapacityOption_7211DDBE50E66221552276C22A5AC2CE" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityAbstract_6B5EBE6F193B5ED53C2476C22A5A8CD5" xlink:to="loc_mg_LineOfCreditFacilityAccordionFeatureHigherBorrowingCapacityOption_7211DDBE50E66221552276C22A5AC2CE" xlink:type="arc" />
    <loc xlink:href="mg-20160831.xsd#mg_LineOfCreditFacilityMaximumBorrowingCapacityInNonUSCurrencies" xlink:label="loc_mg_LineOfCreditFacilityMaximumBorrowingCapacityInNonUSCurrencies_159A0708AB68B172AC5776C22A5A0DAB" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityAbstract_6B5EBE6F193B5ED53C2476C22A5A8CD5" xlink:to="loc_mg_LineOfCreditFacilityMaximumBorrowingCapacityInNonUSCurrencies_159A0708AB68B172AC5776C22A5A0DAB" xlink:type="arc" />
    <loc xlink:href="mg-20160831.xsd#mg_LineOfCreditFacilityMaximumBorrowingCapacityAvailableForIssuanceOfLettersOfCredit" xlink:label="loc_mg_LineOfCreditFacilityMaximumBorrowingCapacityAvailableForIssuanceOfLettersOfCredit_630CB95FED6CD47A284E76C22A5AA847" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityAbstract_6B5EBE6F193B5ED53C2476C22A5A8CD5" xlink:to="loc_mg_LineOfCreditFacilityMaximumBorrowingCapacityAvailableForIssuanceOfLettersOfCredit_630CB95FED6CD47A284E76C22A5AA847" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LineOfCredit" xlink:label="loc_us-gaap_LineOfCredit_AFEA288649086D7F486676C22A5B02DA" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityAbstract_6B5EBE6F193B5ED53C2476C22A5A8CD5" xlink:to="loc_us-gaap_LineOfCredit_AFEA288649086D7F486676C22A5B02DA" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LettersOfCreditOutstandingAmount" xlink:label="loc_us-gaap_LettersOfCreditOutstandingAmount_8B04CD825EC7EA43359676C22A5BE698" xlink:type="locator" />
    <definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityAbstract_6B5EBE6F193B5ED53C2476C22A5A8CD5" xlink:to="loc_us-gaap_LettersOfCreditOutstandingAmount_8B04CD825EC7EA43359676C22A5BE698" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DebtInstrumentDescriptionOfVariableRateBasis" xlink:label="loc_us-gaap_DebtInstrumentDescriptionOfVariableRateBasis_3468F75BCF0D67EDF9C776C22A5B1132" xlink:type="locator" />
    <definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityAbstract_6B5EBE6F193B5ED53C2476C22A5A8CD5" xlink:to="loc_us-gaap_DebtInstrumentDescriptionOfVariableRateBasis_3468F75BCF0D67EDF9C776C22A5B1132" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DebtInstrumentBasisSpreadOnVariableRate1" xlink:label="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_08848C988703050B836D76C22A5BCA5E" xlink:type="locator" />
    <definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityAbstract_6B5EBE6F193B5ED53C2476C22A5A8CD5" xlink:to="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_08848C988703050B836D76C22A5BCA5E" xlink:type="arc" />
    <loc xlink:href="mg-20160831.xsd#mg_DebtInstrumentNumberOfFiscalQuartersUsedForCalculationOfFundedDebtLeverageRatio" xlink:label="loc_mg_DebtInstrumentNumberOfFiscalQuartersUsedForCalculationOfFundedDebtLeverageRatio_2B611A702420A1C3485B76C22A5B18F6" xlink:type="locator" />
    <definitionArc order="9" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityAbstract_6B5EBE6F193B5ED53C2476C22A5A8CD5" xlink:to="loc_mg_DebtInstrumentNumberOfFiscalQuartersUsedForCalculationOfFundedDebtLeverageRatio_2B611A702420A1C3485B76C22A5B18F6" xlink:type="arc" />
    <loc xlink:href="mg-20160831.xsd#mg_DebtInstrumentCovenantFundedLeverageRatioConsideredForLowerInterestRateMargin" xlink:label="loc_mg_DebtInstrumentCovenantFundedLeverageRatioConsideredForLowerInterestRateMargin_E49E5C64603AB3B9088376C22A5B19FE" xlink:type="locator" />
    <definitionArc order="10" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityAbstract_6B5EBE6F193B5ED53C2476C22A5A8CD5" xlink:to="loc_mg_DebtInstrumentCovenantFundedLeverageRatioConsideredForLowerInterestRateMargin_E49E5C64603AB3B9088376C22A5B19FE" xlink:type="arc" />
    <loc xlink:href="mg-20160831.xsd#mg_DebtInstrumentCovenantFundedLeverageRatioConsideredForMaximumInterestRateMargin" xlink:label="loc_mg_DebtInstrumentCovenantFundedLeverageRatioConsideredForMaximumInterestRateMargin_AB68602CC588DB8CE15876C22A5B52E4" xlink:type="locator" />
    <definitionArc order="11" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityAbstract_6B5EBE6F193B5ED53C2476C22A5A8CD5" xlink:to="loc_mg_DebtInstrumentCovenantFundedLeverageRatioConsideredForMaximumInterestRateMargin_AB68602CC588DB8CE15876C22A5B52E4" xlink:type="arc" />
    <loc xlink:href="mg-20160831.xsd#mg_DebtInstrumentAdditionalInterestRateDueToFundedDebtLeverageRatioExceedingSpecifiedThreshold" xlink:label="loc_mg_DebtInstrumentAdditionalInterestRateDueToFundedDebtLeverageRatioExceedingSpecifiedThreshold_6434B9670129F3E07E4D76C22A5BF7DB" xlink:type="locator" />
    <definitionArc order="12" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityAbstract_6B5EBE6F193B5ED53C2476C22A5A8CD5" xlink:to="loc_mg_DebtInstrumentAdditionalInterestRateDueToFundedDebtLeverageRatioExceedingSpecifiedThreshold_6434B9670129F3E07E4D76C22A5BF7DB" xlink:type="arc" />
    <loc xlink:href="mg-20160831.xsd#mg_DebtInstrumentCovenantFundedDebtLeverageRatioForAdditionalInterestPayment" xlink:label="loc_mg_DebtInstrumentCovenantFundedDebtLeverageRatioForAdditionalInterestPayment_BF714945D59E32BC16F376C22A5BDC29" xlink:type="locator" />
    <definitionArc order="13" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityAbstract_6B5EBE6F193B5ED53C2476C22A5A8CD5" xlink:to="loc_mg_DebtInstrumentCovenantFundedDebtLeverageRatioForAdditionalInterestPayment_BF714945D59E32BC16F376C22A5BDC29" xlink:type="arc" />
    <loc xlink:href="mg-20160831.xsd#mg_DebtInstrumentCovenantInterestCoverageRatio" xlink:label="loc_mg_DebtInstrumentCovenantInterestCoverageRatio_1963307BB6F9774D365076C22A5B1EDD" xlink:type="locator" />
    <definitionArc order="14" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityAbstract_6B5EBE6F193B5ED53C2476C22A5A8CD5" xlink:to="loc_mg_DebtInstrumentCovenantInterestCoverageRatio_1963307BB6F9774D365076C22A5B1EDD" xlink:type="arc" />
    <loc xlink:href="mg-20160831.xsd#mg_DebtInstrumentPrecedingPeriodUsedForCalculationOfInterestCoverageRatio" xlink:label="loc_mg_DebtInstrumentPrecedingPeriodUsedForCalculationOfInterestCoverageRatio_2EE44B995BB6CDB2397E76C22A5B1A30" xlink:type="locator" />
    <definitionArc order="15" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityAbstract_6B5EBE6F193B5ED53C2476C22A5A8CD5" xlink:to="loc_mg_DebtInstrumentPrecedingPeriodUsedForCalculationOfInterestCoverageRatio_2EE44B995BB6CDB2397E76C22A5B1A30" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LongtermNotesAndLoansCurrentAndNoncurrentAbstract" xlink:label="loc_us-gaap_LongtermNotesAndLoansCurrentAndNoncurrentAbstract_D220CAE05885AD9780B076C22A5BFE24" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_0BE20ADEF0058DBB704676C22A55D171" xlink:to="loc_us-gaap_LongtermNotesAndLoansCurrentAndNoncurrentAbstract_D220CAE05885AD9780B076C22A5BFE24" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DebtInstrumentTerm" xlink:label="loc_us-gaap_DebtInstrumentTerm_3DCC7C2F27DF7417ADA676C22A5B5A31" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermNotesAndLoansCurrentAndNoncurrentAbstract_D220CAE05885AD9780B076C22A5BFE24" xlink:to="loc_us-gaap_DebtInstrumentTerm_3DCC7C2F27DF7417ADA676C22A5B5A31" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DebtInstrumentInterestRateStatedPercentageRateRangeMinimum" xlink:label="loc_us-gaap_DebtInstrumentInterestRateStatedPercentageRateRangeMinimum_39E90C57290CC2EBBBBF76C22A5B733E" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermNotesAndLoansCurrentAndNoncurrentAbstract_D220CAE05885AD9780B076C22A5BFE24" xlink:to="loc_us-gaap_DebtInstrumentInterestRateStatedPercentageRateRangeMinimum_39E90C57290CC2EBBBBF76C22A5B733E" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://www.mistrasgroup.com/role/LongTermDebtScheduleOfLongTermDebtDetails" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DebtInstrumentLineItems" xlink:label="loc_us-gaap_DebtInstrumentLineItems_4153E9C7F0B85AC1A9BEFBE91EBE6D69" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DebtInstrumentTable" xlink:label="loc_us-gaap_DebtInstrumentTable_88E0E8177C5C5B40890F55BE79B3387A" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_4153E9C7F0B85AC1A9BEFBE91EBE6D69" xlink:to="loc_us-gaap_DebtInstrumentTable_88E0E8177C5C5B40890F55BE79B3387A" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LongtermDebtTypeAxis" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_ECDA6AF78E0756908C5613F36C72B264" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_88E0E8177C5C5B40890F55BE79B3387A" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_ECDA6AF78E0756908C5613F36C72B264" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LongtermDebtTypeDomain" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_D76DEF77F05C8CCB0D65213AD6E2D9EB_90BB69DE126A573BBF1FAEEB3B6E39CC" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_ECDA6AF78E0756908C5613F36C72B264" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_D76DEF77F05C8CCB0D65213AD6E2D9EB_90BB69DE126A573BBF1FAEEB3B6E39CC" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LongtermDebtTypeDomain" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_FE7FCD433C145EC0B1254762AE63D5B2" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_ECDA6AF78E0756908C5613F36C72B264" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_FE7FCD433C145EC0B1254762AE63D5B2" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_RevolvingCreditFacilityMember" xlink:label="loc_us-gaap_RevolvingCreditFacilityMember_44335066F48352B4BF306D709E7D9D52" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_FE7FCD433C145EC0B1254762AE63D5B2" xlink:to="loc_us-gaap_RevolvingCreditFacilityMember_44335066F48352B4BF306D709E7D9D52" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_NotesPayableOtherPayablesMember" xlink:label="loc_us-gaap_NotesPayableOtherPayablesMember_1DA98BDCD8E05A8DA252140D0DA9ED49" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_FE7FCD433C145EC0B1254762AE63D5B2" xlink:to="loc_us-gaap_NotesPayableOtherPayablesMember_1DA98BDCD8E05A8DA252140D0DA9ED49" xlink:type="arc" />
    <loc xlink:href="mg-20160831.xsd#mg_OtherLongTermDebtMember" xlink:label="loc_mg_OtherLongTermDebtMember_7074444C4C475D6695637EB44BB9BCB3" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_FE7FCD433C145EC0B1254762AE63D5B2" xlink:to="loc_mg_OtherLongTermDebtMember_7074444C4C475D6695637EB44BB9BCB3" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LongTermDebt" xlink:label="loc_us-gaap_LongTermDebt_C611571FDA685ED697574970F8B388FE" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_4153E9C7F0B85AC1A9BEFBE91EBE6D69" xlink:to="loc_us-gaap_LongTermDebt_C611571FDA685ED697574970F8B388FE" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LongTermDebtCurrent" xlink:label="loc_us-gaap_LongTermDebtCurrent_432C923E849553C380054727785A5919" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_4153E9C7F0B85AC1A9BEFBE91EBE6D69" xlink:to="loc_us-gaap_LongTermDebtCurrent_432C923E849553C380054727785A5919" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LongTermDebtNoncurrent" xlink:label="loc_us-gaap_LongTermDebtNoncurrent_4F15F1941D1C535D90BCE8170E585786" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_4153E9C7F0B85AC1A9BEFBE91EBE6D69" xlink:to="loc_us-gaap_LongTermDebtNoncurrent_4F15F1941D1C535D90BCE8170E585786" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://www.mistrasgroup.com/role/LongTermDebtTables" xlink:type="extended" />
  <definitionLink xlink:role="http://www.mistrasgroup.com/role/PropertyPlantAndEquipmentNet" xlink:type="extended" />
  <definitionLink xlink:role="http://www.mistrasgroup.com/role/PropertyPlantAndEquipmentNetDetails" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_PropertyPlantAndEquipmentLineItems" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentLineItems_0A9C60436F9350AFAA4F06012499A00D" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ScheduleOfPropertyPlantAndEquipmentTable" xlink:label="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_8CF0D26BB4885378A298C00372EAFB20" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_0A9C60436F9350AFAA4F06012499A00D" xlink:to="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_8CF0D26BB4885378A298C00372EAFB20" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_B279E57A054151BD92A5838673DC1B1D" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_8CF0D26BB4885378A298C00372EAFB20" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_B279E57A054151BD92A5838673DC1B1D" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_BC02D5F1A7D13FEC908FB0C44F236908_DDC566A23FC25E7A9D2A883A037C0F6B" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_B279E57A054151BD92A5838673DC1B1D" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_BC02D5F1A7D13FEC908FB0C44F236908_DDC566A23FC25E7A9D2A883A037C0F6B" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_C67E9D62DD475BCCA888847C67AD4F7B" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_B279E57A054151BD92A5838673DC1B1D" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_C67E9D62DD475BCCA888847C67AD4F7B" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LandMember" xlink:label="loc_us-gaap_LandMember_6401A37AB3B25FD6953ABCF7C9B6F441" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_C67E9D62DD475BCCA888847C67AD4F7B" xlink:to="loc_us-gaap_LandMember_6401A37AB3B25FD6953ABCF7C9B6F441" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_BuildingAndBuildingImprovementsMember" xlink:label="loc_us-gaap_BuildingAndBuildingImprovementsMember_34D428373C8E528D9898BD849B94163D" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_C67E9D62DD475BCCA888847C67AD4F7B" xlink:to="loc_us-gaap_BuildingAndBuildingImprovementsMember_34D428373C8E528D9898BD849B94163D" xlink:type="arc" />
    <loc xlink:href="mg-20160831.xsd#mg_OfficeFurnitureAndEquipmentMember" xlink:label="loc_mg_OfficeFurnitureAndEquipmentMember_4E4BFC3321FA53538A59357D9BB9553E" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_C67E9D62DD475BCCA888847C67AD4F7B" xlink:to="loc_mg_OfficeFurnitureAndEquipmentMember_4E4BFC3321FA53538A59357D9BB9553E" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_MachineryAndEquipmentMember" xlink:label="loc_us-gaap_MachineryAndEquipmentMember_E42F3790F59C5E07812FD68D26F309C2" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_C67E9D62DD475BCCA888847C67AD4F7B" xlink:to="loc_us-gaap_MachineryAndEquipmentMember_E42F3790F59C5E07812FD68D26F309C2" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_RangeAxis" xlink:label="loc_us-gaap_RangeAxis_CD50405ACF095E619994DDDA79694028" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_8CF0D26BB4885378A298C00372EAFB20" xlink:to="loc_us-gaap_RangeAxis_CD50405ACF095E619994DDDA79694028" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_RangeMember" xlink:label="loc_us-gaap_RangeMember_93463BABD2A5E254CCDBB0C44F23ED02_DDC566A23FC25E7A9D2A883A037C0F6B" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RangeAxis_CD50405ACF095E619994DDDA79694028" xlink:to="loc_us-gaap_RangeMember_93463BABD2A5E254CCDBB0C44F23ED02_DDC566A23FC25E7A9D2A883A037C0F6B" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_RangeMember" xlink:label="loc_us-gaap_RangeMember_0C9E439929795306930E6D5A8BDCF99B" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RangeAxis_CD50405ACF095E619994DDDA79694028" xlink:to="loc_us-gaap_RangeMember_0C9E439929795306930E6D5A8BDCF99B" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_MinimumMember" xlink:label="loc_us-gaap_MinimumMember_F716AB118B2256A68F459A186D3F5782" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RangeMember_0C9E439929795306930E6D5A8BDCF99B" xlink:to="loc_us-gaap_MinimumMember_F716AB118B2256A68F459A186D3F5782" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_MaximumMember" xlink:label="loc_us-gaap_MaximumMember_B1237BF13640595FA6C97B9FD4EFDE9E" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RangeMember_0C9E439929795306930E6D5A8BDCF99B" xlink:to="loc_us-gaap_MaximumMember_B1237BF13640595FA6C97B9FD4EFDE9E" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_PropertyPlantAndEquipmentUsefulLife" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentUsefulLife_2D126B44F042575BBB07EEDDACF8FCEC" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_0A9C60436F9350AFAA4F06012499A00D" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentUsefulLife_2D126B44F042575BBB07EEDDACF8FCEC" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_PropertyPlantAndEquipmentGross" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentGross_532CD79A2DF75AE3B60D1619F500CEFB" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_0A9C60436F9350AFAA4F06012499A00D" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentGross_532CD79A2DF75AE3B60D1619F500CEFB" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment" xlink:label="loc_us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment_DB27FC1CB9245EE1B065C616AF171836" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_0A9C60436F9350AFAA4F06012499A00D" xlink:to="loc_us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment_DB27FC1CB9245EE1B065C616AF171836" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_PropertyPlantAndEquipmentNet" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentNet_0B49577C29FF58AFA5EAA40036FA1593" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_0A9C60436F9350AFAA4F06012499A00D" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentNet_0B49577C29FF58AFA5EAA40036FA1593" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://www.mistrasgroup.com/role/PropertyPlantAndEquipmentNetTables" xlink:type="extended" />
  <definitionLink xlink:role="http://www.mistrasgroup.com/role/SegmentDisclosure" xlink:type="extended" />
  <definitionLink xlink:role="http://www.mistrasgroup.com/role/SegmentDisclosureFinancialInformationBySegmentDetails" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_SegmentReportingInformationLineItems" xlink:label="loc_us-gaap_SegmentReportingInformationLineItems_62B013E3384CD46AFDD176C229FA764A" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable" xlink:label="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_D0E785FC83BC67277EF776C229F48787" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_62B013E3384CD46AFDD176C229FA764A" xlink:to="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_D0E785FC83BC67277EF776C229F48787" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ConsolidationItemsAxis" xlink:label="loc_us-gaap_ConsolidationItemsAxis_715777381AE0622CF40776C229F44D3B" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_D0E785FC83BC67277EF776C229F48787" xlink:to="loc_us-gaap_ConsolidationItemsAxis_715777381AE0622CF40776C229F44D3B" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ConsolidationItemsDomain" xlink:label="loc_us-gaap_ConsolidationItemsDomain_3BA87CF20289FFC6644B76C229F9442B_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConsolidationItemsAxis_715777381AE0622CF40776C229F44D3B" xlink:to="loc_us-gaap_ConsolidationItemsDomain_3BA87CF20289FFC6644B76C229F9442B_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ConsolidationItemsDomain" xlink:label="loc_us-gaap_ConsolidationItemsDomain_3BA87CF20289FFC6644B76C229F9442B" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConsolidationItemsAxis_715777381AE0622CF40776C229F44D3B" xlink:to="loc_us-gaap_ConsolidationItemsDomain_3BA87CF20289FFC6644B76C229F9442B" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_OperatingSegmentsMember" xlink:label="loc_us-gaap_OperatingSegmentsMember_34378614161E6676215376C229F9B14D" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConsolidationItemsDomain_3BA87CF20289FFC6644B76C229F9442B" xlink:to="loc_us-gaap_OperatingSegmentsMember_34378614161E6676215376C229F9B14D" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_IntersegmentEliminationMember" xlink:label="loc_us-gaap_IntersegmentEliminationMember_742526880390EDC2228376C229FA35F2" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConsolidationItemsDomain_3BA87CF20289FFC6644B76C229F9442B" xlink:to="loc_us-gaap_IntersegmentEliminationMember_742526880390EDC2228376C229FA35F2" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_StatementBusinessSegmentsAxis" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_495790AB29D0CFE1AC0676C229FA2314" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_D0E785FC83BC67277EF776C229F48787" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_495790AB29D0CFE1AC0676C229FA2314" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_SegmentDomain" xlink:label="loc_us-gaap_SegmentDomain_8F3491AA9568848E54ED76C229FACAF5_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_495790AB29D0CFE1AC0676C229FA2314" xlink:to="loc_us-gaap_SegmentDomain_8F3491AA9568848E54ED76C229FACAF5_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_SegmentDomain" xlink:label="loc_us-gaap_SegmentDomain_8F3491AA9568848E54ED76C229FACAF5" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_495790AB29D0CFE1AC0676C229FA2314" xlink:to="loc_us-gaap_SegmentDomain_8F3491AA9568848E54ED76C229FACAF5" xlink:type="arc" />
    <loc xlink:href="mg-20160831.xsd#mg_ServicesMember" xlink:label="loc_mg_ServicesMember_D312C944256344B9CED576C229FAE591" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_8F3491AA9568848E54ED76C229FACAF5" xlink:to="loc_mg_ServicesMember_D312C944256344B9CED576C229FAE591" xlink:type="arc" />
    <loc xlink:href="mg-20160831.xsd#mg_InternationalMember" xlink:label="loc_mg_InternationalMember_D4FC8F1A52AB165C1C8A76C229FA6549" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_8F3491AA9568848E54ED76C229FACAF5" xlink:to="loc_mg_InternationalMember_D4FC8F1A52AB165C1C8A76C229FA6549" xlink:type="arc" />
    <loc xlink:href="mg-20160831.xsd#mg_ProductsAndSystemsMember" xlink:label="loc_mg_ProductsAndSystemsMember_0BD7784B5D766046A42C76C229FA63F6" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_8F3491AA9568848E54ED76C229FACAF5" xlink:to="loc_mg_ProductsAndSystemsMember_0BD7784B5D766046A42C76C229FA63F6" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_SalesRevenueNet" xlink:label="loc_us-gaap_SalesRevenueNet_FC9910C53DD338A81F0376C229FABF10" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_62B013E3384CD46AFDD176C229FA764A" xlink:to="loc_us-gaap_SalesRevenueNet_FC9910C53DD338A81F0376C229FABF10" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_GrossProfit" xlink:label="loc_us-gaap_GrossProfit_536901D68AA8043C970E76C229FA9C6B" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_62B013E3384CD46AFDD176C229FA764A" xlink:to="loc_us-gaap_GrossProfit_536901D68AA8043C970E76C229FA9C6B" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_OperatingIncomeLoss" xlink:label="loc_us-gaap_OperatingIncomeLoss_C13FF287886796FCA10D76C229FA4A7C" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_62B013E3384CD46AFDD176C229FA764A" xlink:to="loc_us-gaap_OperatingIncomeLoss_C13FF287886796FCA10D76C229FA4A7C" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DepreciationDepletionAndAmortization" xlink:label="loc_us-gaap_DepreciationDepletionAndAmortization_E9F076D02963D31F0A7276C229FABE17" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_62B013E3384CD46AFDD176C229FA764A" xlink:to="loc_us-gaap_DepreciationDepletionAndAmortization_E9F076D02963D31F0A7276C229FABE17" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_IntangibleAssetsNetExcludingGoodwill" xlink:label="loc_us-gaap_IntangibleAssetsNetExcludingGoodwill_29D209AB53F768976CFF76DA42AB9E94" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_62B013E3384CD46AFDD176C229FA764A" xlink:to="loc_us-gaap_IntangibleAssetsNetExcludingGoodwill_29D209AB53F768976CFF76DA42AB9E94" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_Assets" xlink:label="loc_us-gaap_Assets_8591B7C6376FA52DC24976C229FA6B41" xlink:type="locator" />
    <definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_62B013E3384CD46AFDD176C229FA764A" xlink:to="loc_us-gaap_Assets_8591B7C6376FA52DC24976C229FA6B41" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://www.mistrasgroup.com/role/SegmentDisclosureRevenuesByGeographicAreaDetails" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems" xlink:label="loc_us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems_7BEC97604A2655E1ABCF8E1F5ADB768A" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ScheduleOfRevenuesFromExternalCustomersAndLongLivedAssetsTable" xlink:label="loc_us-gaap_ScheduleOfRevenuesFromExternalCustomersAndLongLivedAssetsTable_94BA6FD59382561297A82D046D7E1F4B" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems_7BEC97604A2655E1ABCF8E1F5ADB768A" xlink:to="loc_us-gaap_ScheduleOfRevenuesFromExternalCustomersAndLongLivedAssetsTable_94BA6FD59382561297A82D046D7E1F4B" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_StatementGeographicalAxis" xlink:label="loc_us-gaap_StatementGeographicalAxis_B915C760C0A6525DB0680CBA33A1A447" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRevenuesFromExternalCustomersAndLongLivedAssetsTable_94BA6FD59382561297A82D046D7E1F4B" xlink:to="loc_us-gaap_StatementGeographicalAxis_B915C760C0A6525DB0680CBA33A1A447" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_SegmentGeographicalDomain" xlink:label="loc_us-gaap_SegmentGeographicalDomain_0508998665F8D47C5EA74AC387AB5F59_90BB69DE126A573BBF1FAEEB3B6E39CC" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementGeographicalAxis_B915C760C0A6525DB0680CBA33A1A447" xlink:to="loc_us-gaap_SegmentGeographicalDomain_0508998665F8D47C5EA74AC387AB5F59_90BB69DE126A573BBF1FAEEB3B6E39CC" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_SegmentGeographicalDomain" xlink:label="loc_us-gaap_SegmentGeographicalDomain_B04018257CC15F0A9220C262D4DAF2F7" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementGeographicalAxis_B915C760C0A6525DB0680CBA33A1A447" xlink:to="loc_us-gaap_SegmentGeographicalDomain_B04018257CC15F0A9220C262D4DAF2F7" xlink:type="arc" />
    <loc xlink:href="http://xbrl.sec.gov/country/2013/country-2013-01-31.xsd#country_US" xlink:label="loc_country_US_33FFD35E8B265C998E8335FAAC943319" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentGeographicalDomain_B04018257CC15F0A9220C262D4DAF2F7" xlink:to="loc_country_US_33FFD35E8B265C998E8335FAAC943319" xlink:type="arc" />
    <loc xlink:href="mg-20160831.xsd#mg_OtherAmericasMember" xlink:label="loc_mg_OtherAmericasMember_120D74D676EE50AA8DA9327A3916A9DD" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentGeographicalDomain_B04018257CC15F0A9220C262D4DAF2F7" xlink:to="loc_mg_OtherAmericasMember_120D74D676EE50AA8DA9327A3916A9DD" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_EuropeMember" xlink:label="loc_us-gaap_EuropeMember_D8B9EAD94C305CA2925D4E26A1018EAF" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentGeographicalDomain_B04018257CC15F0A9220C262D4DAF2F7" xlink:to="loc_us-gaap_EuropeMember_D8B9EAD94C305CA2925D4E26A1018EAF" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AsiaPacificMember" xlink:label="loc_us-gaap_AsiaPacificMember_E46EF55E769B523EA8826086153DBC14" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentGeographicalDomain_B04018257CC15F0A9220C262D4DAF2F7" xlink:to="loc_us-gaap_AsiaPacificMember_E46EF55E769B523EA8826086153DBC14" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_SalesRevenueNet" xlink:label="loc_us-gaap_SalesRevenueNet_46C8DE44C91F59DFA751A7096EE8A817" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems_7BEC97604A2655E1ABCF8E1F5ADB768A" xlink:to="loc_us-gaap_SalesRevenueNet_46C8DE44C91F59DFA751A7096EE8A817" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://www.mistrasgroup.com/role/SegmentDisclosureTables" xlink:type="extended" />
  <definitionLink xlink:role="http://www.mistrasgroup.com/role/ShareBasedCompensation" xlink:type="extended" />
  <definitionLink xlink:role="http://www.mistrasgroup.com/role/ShareBasedCompensationAdditionalInformationDetails" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_F6CAED0006F908BC8DD38BC1958C9ED5" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_CA01811B710C5B9395158BC1958CDE45" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_F6CAED0006F908BC8DD38BC1958C9ED5" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_CA01811B710C5B9395158BC1958CDE45" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_PlanNameAxis" xlink:label="loc_us-gaap_PlanNameAxis_370CC79B2C2B806C90098BC1958C57B0" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_CA01811B710C5B9395158BC1958CDE45" xlink:to="loc_us-gaap_PlanNameAxis_370CC79B2C2B806C90098BC1958C57B0" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_PlanNameDomain" xlink:label="loc_us-gaap_PlanNameDomain_97D96326B7B7695E946E8BC1958C1BD4_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PlanNameAxis_370CC79B2C2B806C90098BC1958C57B0" xlink:to="loc_us-gaap_PlanNameDomain_97D96326B7B7695E946E8BC1958C1BD4_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_PlanNameDomain" xlink:label="loc_us-gaap_PlanNameDomain_97D96326B7B7695E946E8BC1958C1BD4" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PlanNameAxis_370CC79B2C2B806C90098BC1958C57B0" xlink:to="loc_us-gaap_PlanNameDomain_97D96326B7B7695E946E8BC1958C1BD4" xlink:type="arc" />
    <loc xlink:href="mg-20160831.xsd#mg_StockOptionPlan2007Member" xlink:label="loc_mg_StockOptionPlan2007Member_0A83A542D5D96178F7088BC1958CCF8D" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_97D96326B7B7695E946E8BC1958C1BD4" xlink:to="loc_mg_StockOptionPlan2007Member_0A83A542D5D96178F7088BC1958CCF8D" xlink:type="arc" />
    <loc xlink:href="mg-20160831.xsd#mg_NumberOfEmployeeShareBasedPlans" xlink:label="loc_mg_NumberOfEmployeeShareBasedPlans_814EE295D292D11DD4A18BC1958CB1C0" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_F6CAED0006F908BC8DD38BC1958C9ED5" xlink:to="loc_mg_NumberOfEmployeeShareBasedPlans_814EE295D292D11DD4A18BC1958CB1C0" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant_3D3EB73CA64633FB75E78BC1958CF704" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_F6CAED0006F908BC8DD38BC1958C9ED5" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant_3D3EB73CA64633FB75E78BC1958CF704" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://www.mistrasgroup.com/role/ShareBasedCompensationPerformanceRestrictedStockUnitsActivityDetails" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_EA2229E10468BF66C49FA05CC5643869" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_F708E416D4B65CD3D294A05CC5637C7E" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_EA2229E10468BF66C49FA05CC5643869" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_F708E416D4B65CD3D294A05CC5637C7E" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AwardTypeAxis" xlink:label="loc_us-gaap_AwardTypeAxis_D0297D7BEB6FC18FF9B9A05CC563A7E8" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_F708E416D4B65CD3D294A05CC5637C7E" xlink:to="loc_us-gaap_AwardTypeAxis_D0297D7BEB6FC18FF9B9A05CC563A7E8" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_1AA03433662E4B32EA62A05CC5642BC5_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_D0297D7BEB6FC18FF9B9A05CC563A7E8" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_1AA03433662E4B32EA62A05CC5642BC5_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_1AA03433662E4B32EA62A05CC5642BC5" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_D0297D7BEB6FC18FF9B9A05CC563A7E8" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_1AA03433662E4B32EA62A05CC5642BC5" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_PerformanceSharesMember" xlink:label="loc_us-gaap_PerformanceSharesMember_8122F2931335267D941EA05CC5641239" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_1AA03433662E4B32EA62A05CC5642BC5" xlink:to="loc_us-gaap_PerformanceSharesMember_8122F2931335267D941EA05CC5641239" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_95C9A323A985A3D7C77FA05CC564C6E2" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_EA2229E10468BF66C49FA05CC5643869" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_95C9A323A985A3D7C77FA05CC564C6E2" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_800801966775672A9E6FA05CC564F195" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_95C9A323A985A3D7C77FA05CC564C6E2" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_800801966775672A9E6FA05CC564F195" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_33BB527C4F4F2BF78D74A05CC56492F3" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_95C9A323A985A3D7C77FA05CC564C6E2" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_33BB527C4F4F2BF78D74A05CC56492F3" xlink:type="arc" />
    <loc xlink:href="mg-20160831.xsd#mg_SharebasedCompensationArrangementbySharebasedPaymentAwardEquityInstrumentsOtherthanOptionsAdjustmentsinPeriod" xlink:label="loc_mg_SharebasedCompensationArrangementbySharebasedPaymentAwardEquityInstrumentsOtherthanOptionsAdjustmentsinPeriod_79AA0799C285BE1955ECA069CB861BEE" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_95C9A323A985A3D7C77FA05CC564C6E2" xlink:to="loc_mg_SharebasedCompensationArrangementbySharebasedPaymentAwardEquityInstrumentsOtherthanOptionsAdjustmentsinPeriod_79AA0799C285BE1955ECA069CB861BEE" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_984E81B88E5CADB6EACBA05CC564D19A" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_95C9A323A985A3D7C77FA05CC564C6E2" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_984E81B88E5CADB6EACBA05CC564D19A" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_0811DE1E1F2EF7FA085AA05CC564EA5B" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_95C9A323A985A3D7C77FA05CC564C6E2" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_0811DE1E1F2EF7FA085AA05CC564EA5B" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedWeightedAverageGrantDateFairValueAbstract" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedWeightedAverageGrantDateFairValueAbstract_D93684073A6EB8AD7474A05CC56470E5" xlink:type="locator" />
    <definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_95C9A323A985A3D7C77FA05CC564C6E2" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedWeightedAverageGrantDateFairValueAbstract_D93684073A6EB8AD7474A05CC56470E5" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_D2B37705B297E14D0AB7A05CC564C7CC" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedWeightedAverageGrantDateFairValueAbstract_D93684073A6EB8AD7474A05CC56470E5" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_D2B37705B297E14D0AB7A05CC564C7CC" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_B5C2F117E90AE553E856A05CC564383F" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedWeightedAverageGrantDateFairValueAbstract_D93684073A6EB8AD7474A05CC56470E5" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_B5C2F117E90AE553E856A05CC564383F" xlink:type="arc" />
    <loc xlink:href="mg-20160831.xsd#mg_SharebasedCompensationArrangementbySharebasedPaymentAwardEquityInstrumentsOtherthanOptionsAdjustmentsinPeriodWeightedAverageGrantDateFairValue" xlink:label="loc_mg_SharebasedCompensationArrangementbySharebasedPaymentAwardEquityInstrumentsOtherthanOptionsAdjustmentsinPeriodWeightedAverageGrantDateFairValue_DBF2D40EBD18C26F9B34A05CC564DD70" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedWeightedAverageGrantDateFairValueAbstract_D93684073A6EB8AD7474A05CC56470E5" xlink:to="loc_mg_SharebasedCompensationArrangementbySharebasedPaymentAwardEquityInstrumentsOtherthanOptionsAdjustmentsinPeriodWeightedAverageGrantDateFairValue_DBF2D40EBD18C26F9B34A05CC564DD70" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_E6B7F8741CA36D302525A05CC5640527" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedWeightedAverageGrantDateFairValueAbstract_D93684073A6EB8AD7474A05CC56470E5" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_E6B7F8741CA36D302525A05CC5640527" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_A509D88713423950E701A05CC569BE78" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedWeightedAverageGrantDateFairValueAbstract_D93684073A6EB8AD7474A05CC56470E5" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_A509D88713423950E701A05CC569BE78" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://www.mistrasgroup.com/role/ShareBasedCompensationPerformanceRestrictedStockUnitsNarrativeDetails" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_A83D99C62007ECB67371A05CC57A13BE" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_360547EEE1525000278DA05CC5794F0C" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_A83D99C62007ECB67371A05CC57A13BE" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_360547EEE1525000278DA05CC5794F0C" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AwardTypeAxis" xlink:label="loc_us-gaap_AwardTypeAxis_F464846B7E75BD36ED9DA05CC5795573" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_360547EEE1525000278DA05CC5794F0C" xlink:to="loc_us-gaap_AwardTypeAxis_F464846B7E75BD36ED9DA05CC5795573" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_322FACEEE2ED7C2680F2A05CC57993DC_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_F464846B7E75BD36ED9DA05CC5795573" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_322FACEEE2ED7C2680F2A05CC57993DC_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_322FACEEE2ED7C2680F2A05CC57993DC" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_F464846B7E75BD36ED9DA05CC5795573" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_322FACEEE2ED7C2680F2A05CC57993DC" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_PerformanceSharesMember" xlink:label="loc_us-gaap_PerformanceSharesMember_0BC42A4ABF7B07D40637A05CC579AA26" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_322FACEEE2ED7C2680F2A05CC57993DC" xlink:to="loc_us-gaap_PerformanceSharesMember_0BC42A4ABF7B07D40637A05CC579AA26" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AwardDateAxis" xlink:label="loc_us-gaap_AwardDateAxis_5FCD2BA6015A8DCC83BEA05CC579DCDD" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_360547EEE1525000278DA05CC5794F0C" xlink:to="loc_us-gaap_AwardDateAxis_5FCD2BA6015A8DCC83BEA05CC579DCDD" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AwardDateDomain" xlink:label="loc_us-gaap_AwardDateDomain_D335838BC1E0D08D055AA05CC57A2B7F_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardDateAxis_5FCD2BA6015A8DCC83BEA05CC579DCDD" xlink:to="loc_us-gaap_AwardDateDomain_D335838BC1E0D08D055AA05CC57A2B7F_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AwardDateDomain" xlink:label="loc_us-gaap_AwardDateDomain_D335838BC1E0D08D055AA05CC57A2B7F" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardDateAxis_5FCD2BA6015A8DCC83BEA05CC579DCDD" xlink:to="loc_us-gaap_AwardDateDomain_D335838BC1E0D08D055AA05CC57A2B7F" xlink:type="arc" />
    <loc xlink:href="mg-20160831.xsd#mg_Fiscal2016GrantsMember" xlink:label="loc_mg_Fiscal2016GrantsMember_4D27F14DFFA92641B0BAA05CC57A7240" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AwardDateDomain_D335838BC1E0D08D055AA05CC57A2B7F" xlink:to="loc_mg_Fiscal2016GrantsMember_4D27F14DFFA92641B0BAA05CC57A7240" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_TitleOfIndividualAxis" xlink:label="loc_us-gaap_TitleOfIndividualAxis_D360C4E8C63F0BD913E1A05CC57A3E2C" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_360547EEE1525000278DA05CC5794F0C" xlink:to="loc_us-gaap_TitleOfIndividualAxis_D360C4E8C63F0BD913E1A05CC57A3E2C" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_TitleOfIndividualWithRelationshipToEntityDomain" xlink:label="loc_us-gaap_TitleOfIndividualWithRelationshipToEntityDomain_11775EE599A43DF24480A05CC57A27F7_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_TitleOfIndividualAxis_D360C4E8C63F0BD913E1A05CC57A3E2C" xlink:to="loc_us-gaap_TitleOfIndividualWithRelationshipToEntityDomain_11775EE599A43DF24480A05CC57A27F7_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_TitleOfIndividualWithRelationshipToEntityDomain" xlink:label="loc_us-gaap_TitleOfIndividualWithRelationshipToEntityDomain_11775EE599A43DF24480A05CC57A27F7" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_TitleOfIndividualAxis_D360C4E8C63F0BD913E1A05CC57A3E2C" xlink:to="loc_us-gaap_TitleOfIndividualWithRelationshipToEntityDomain_11775EE599A43DF24480A05CC57A27F7" xlink:type="arc" />
    <loc xlink:href="mg-20160831.xsd#mg_ExecutiveAndSeniorOfficersMember" xlink:label="loc_mg_ExecutiveAndSeniorOfficersMember_ED48B940CC043F7CB9A0A05CC57ADAD4" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TitleOfIndividualWithRelationshipToEntityDomain_11775EE599A43DF24480A05CC57A27F7" xlink:to="loc_mg_ExecutiveAndSeniorOfficersMember_ED48B940CC043F7CB9A0A05CC57ADAD4" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_BalanceSheetLocationAxis" xlink:label="loc_us-gaap_BalanceSheetLocationAxis_8BD07C827F00934DBAC2A05CC57AAFAD" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_360547EEE1525000278DA05CC5794F0C" xlink:to="loc_us-gaap_BalanceSheetLocationAxis_8BD07C827F00934DBAC2A05CC57AAFAD" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_BalanceSheetLocationDomain" xlink:label="loc_us-gaap_BalanceSheetLocationDomain_838B7DD2335A1C9A2A47A05CC57A8679_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BalanceSheetLocationAxis_8BD07C827F00934DBAC2A05CC57AAFAD" xlink:to="loc_us-gaap_BalanceSheetLocationDomain_838B7DD2335A1C9A2A47A05CC57A8679_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_BalanceSheetLocationDomain" xlink:label="loc_us-gaap_BalanceSheetLocationDomain_838B7DD2335A1C9A2A47A05CC57A8679" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BalanceSheetLocationAxis_8BD07C827F00934DBAC2A05CC57AAFAD" xlink:to="loc_us-gaap_BalanceSheetLocationDomain_838B7DD2335A1C9A2A47A05CC57A8679" xlink:type="arc" />
    <loc xlink:href="mg-20160831.xsd#mg_AccruedExpensesandOtherCurrentLiabilitiesMember" xlink:label="loc_mg_AccruedExpensesandOtherCurrentLiabilitiesMember_308A6E7728175DE865F2A05CC57AF934" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BalanceSheetLocationDomain_838B7DD2335A1C9A2A47A05CC57A8679" xlink:to="loc_mg_AccruedExpensesandOtherCurrentLiabilitiesMember_308A6E7728175DE865F2A05CC57AF934" xlink:type="arc" />
    <loc xlink:href="mg-20160831.xsd#mg_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardPerformancePeriod" xlink:label="loc_mg_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardPerformancePeriod_4C80BD8E894B6D9D969FA05CC57A59AC" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_A83D99C62007ECB67371A05CC57A13BE" xlink:to="loc_mg_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardPerformancePeriod_4C80BD8E894B6D9D969FA05CC57A59AC" xlink:type="arc" />
    <loc xlink:href="mg-20160831.xsd#mg_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfAwardMetrics" xlink:label="loc_mg_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfAwardMetrics_21C9A845400E43DAE4D1A05CC57A8534" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_A83D99C62007ECB67371A05CC57A13BE" xlink:to="loc_mg_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfAwardMetrics_21C9A845400E43DAE4D1A05CC57A8534" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardRequisiteServicePeriod1" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardRequisiteServicePeriod1_914A3ED811EEBE5AB33EA05CC57AEA5E" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_A83D99C62007ECB67371A05CC57A13BE" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardRequisiteServicePeriod1_914A3ED811EEBE5AB33EA05CC57AEA5E" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfAdditionalSharesAuthorized" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfAdditionalSharesAuthorized_48106D4636A5EE28BDE0A05CC57A008B" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_A83D99C62007ECB67371A05CC57A13BE" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfAdditionalSharesAuthorized_48106D4636A5EE28BDE0A05CC57A008B" xlink:type="arc" />
    <loc xlink:href="mg-20160831.xsd#mg_SharebasedCompensationArrangementbySharebasedPaymentAwardRemainingNumberofAuthorizedShares" xlink:label="loc_mg_SharebasedCompensationArrangementbySharebasedPaymentAwardRemainingNumberofAuthorizedShares_22E0D12260FBFEBDA85CA05CC57AA468" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_A83D99C62007ECB67371A05CC57A13BE" xlink:to="loc_mg_SharebasedCompensationArrangementbySharebasedPaymentAwardRemainingNumberofAuthorizedShares_22E0D12260FBFEBDA85CA05CC57AA468" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AccruedLiabilitiesCurrent" xlink:label="loc_us-gaap_AccruedLiabilitiesCurrent_41CB062D547E3B3A4055A05CC57A432B" xlink:type="locator" />
    <definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_A83D99C62007ECB67371A05CC57A13BE" xlink:to="loc_us-gaap_AccruedLiabilitiesCurrent_41CB062D547E3B3A4055A05CC57A432B" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AllocatedShareBasedCompensationExpense" xlink:label="loc_us-gaap_AllocatedShareBasedCompensationExpense_51A84544EC9E20B5DACCA05CC57A6758" xlink:type="locator" />
    <definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_A83D99C62007ECB67371A05CC57A13BE" xlink:to="loc_us-gaap_AllocatedShareBasedCompensationExpense_51A84544EC9E20B5DACCA05CC57A6758" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedShareBasedAwardsOtherThanOptions" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedShareBasedAwardsOtherThanOptions_4E5A2FA71613612812F3A05CC57B4A1B" xlink:type="locator" />
    <definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_A83D99C62007ECB67371A05CC57A13BE" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedShareBasedAwardsOtherThanOptions_4E5A2FA71613612812F3A05CC57B4A1B" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_C2FDA1B9B6D585B36254A05CC57BD60D" xlink:type="locator" />
    <definitionArc order="9" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_A83D99C62007ECB67371A05CC57A13BE" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_C2FDA1B9B6D585B36254A05CC57BD60D" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_32E3B75B2D80F7B2456AA05CC57B9DE0" xlink:type="locator" />
    <definitionArc order="10" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_A83D99C62007ECB67371A05CC57A13BE" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_32E3B75B2D80F7B2456AA05CC57B9DE0" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://www.mistrasgroup.com/role/ShareBasedCompensationRestrictedStockUnitAwardsNarrativeDetails" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_CA9CDE8A4665F52CB4C976E464DDEA8F" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_F7B001703C6BD12E344A76E464DD7C24" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_CA9CDE8A4665F52CB4C976E464DDEA8F" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_F7B001703C6BD12E344A76E464DD7C24" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AwardTypeAxis" xlink:label="loc_us-gaap_AwardTypeAxis_0D317756DB8A6B9C384176E464DD0A22" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_F7B001703C6BD12E344A76E464DD7C24" xlink:to="loc_us-gaap_AwardTypeAxis_0D317756DB8A6B9C384176E464DD0A22" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_824DDF5C851A058862B776E464DD7240_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_0D317756DB8A6B9C384176E464DD0A22" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_824DDF5C851A058862B776E464DD7240_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_824DDF5C851A058862B776E464DD7240" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_0D317756DB8A6B9C384176E464DD0A22" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_824DDF5C851A058862B776E464DD7240" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_RestrictedStockUnitsRSUMember" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_94E5BBDC509DE2E0D9D576E464DD2E43" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_824DDF5C851A058862B776E464DD7240" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_94E5BBDC509DE2E0D9D576E464DD2E43" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_TitleOfIndividualAxis" xlink:label="loc_us-gaap_TitleOfIndividualAxis_42445E91579C2E33318A76E464DD5E14" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_F7B001703C6BD12E344A76E464DD7C24" xlink:to="loc_us-gaap_TitleOfIndividualAxis_42445E91579C2E33318A76E464DD5E14" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_TitleOfIndividualWithRelationshipToEntityDomain" xlink:label="loc_us-gaap_TitleOfIndividualWithRelationshipToEntityDomain_6F4D9506F61907D497FF76E464DDF225_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_TitleOfIndividualAxis_42445E91579C2E33318A76E464DD5E14" xlink:to="loc_us-gaap_TitleOfIndividualWithRelationshipToEntityDomain_6F4D9506F61907D497FF76E464DDF225_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_TitleOfIndividualWithRelationshipToEntityDomain" xlink:label="loc_us-gaap_TitleOfIndividualWithRelationshipToEntityDomain_6F4D9506F61907D497FF76E464DDF225" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_TitleOfIndividualAxis_42445E91579C2E33318A76E464DD5E14" xlink:to="loc_us-gaap_TitleOfIndividualWithRelationshipToEntityDomain_6F4D9506F61907D497FF76E464DDF225" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DirectorMember" xlink:label="loc_us-gaap_DirectorMember_9B354CBC56E030D34A5E76E464DD4B16" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TitleOfIndividualWithRelationshipToEntityDomain_6F4D9506F61907D497FF76E464DDF225" xlink:to="loc_us-gaap_DirectorMember_9B354CBC56E030D34A5E76E464DD4B16" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AllocatedShareBasedCompensationExpense" xlink:label="loc_us-gaap_AllocatedShareBasedCompensationExpense_24D8C767F849B1E11AFF76E464DD5268" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_CA9CDE8A4665F52CB4C976E464DDEA8F" xlink:to="loc_us-gaap_AllocatedShareBasedCompensationExpense_24D8C767F849B1E11AFF76E464DD5268" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedShareBasedAwardsOtherThanOptions" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedShareBasedAwardsOtherThanOptions_36378AC48DE1170938A476E464DDCE3F" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_CA9CDE8A4665F52CB4C976E464DDEA8F" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedShareBasedAwardsOtherThanOptions_36378AC48DE1170938A476E464DDCE3F" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_1FD3E33C4D466DF8E59D76E464DE5DB7" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_CA9CDE8A4665F52CB4C976E464DDEA8F" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_1FD3E33C4D466DF8E59D76E464DE5DB7" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue_DEC66CBCFC71A527FCAD76E464DE9AB2" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_CA9CDE8A4665F52CB4C976E464DDEA8F" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue_DEC66CBCFC71A527FCAD76E464DE9AB2" xlink:type="arc" />
    <loc xlink:href="mg-20160831.xsd#mg_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfNonEmployeeDirectorsToWhomAwardIsGranted" xlink:label="loc_mg_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfNonEmployeeDirectorsToWhomAwardIsGranted_3C89344D2F0FEB79FF0B76E464DE9303" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_CA9CDE8A4665F52CB4C976E464DDEA8F" xlink:to="loc_mg_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfNonEmployeeDirectorsToWhomAwardIsGranted_3C89344D2F0FEB79FF0B76E464DE9303" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsGranted" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsGranted_0DBCB9935B7C1878780F76E464DE7363" xlink:type="locator" />
    <definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_CA9CDE8A4665F52CB4C976E464DDEA8F" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsGranted_0DBCB9935B7C1878780F76E464DE7363" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_2DB564F954747B4F298076E464DE71C1" xlink:type="locator" />
    <definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_CA9CDE8A4665F52CB4C976E464DDEA8F" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_2DB564F954747B4F298076E464DE71C1" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://www.mistrasgroup.com/role/ShareBasedCompensationRestrictedStockUnitsAwardsActivityDetails" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_61E0618F683F19AC1AA7A05CC588217C" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_176EE39F616F2E162703A05CC5881169" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_61E0618F683F19AC1AA7A05CC588217C" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_176EE39F616F2E162703A05CC5881169" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AwardTypeAxis" xlink:label="loc_us-gaap_AwardTypeAxis_6AC817F8C9BF272AF1A8A05CC588F5B1" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_176EE39F616F2E162703A05CC5881169" xlink:to="loc_us-gaap_AwardTypeAxis_6AC817F8C9BF272AF1A8A05CC588F5B1" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_FBBA1CA224BD8A3BC542A05CC588B0B9_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_6AC817F8C9BF272AF1A8A05CC588F5B1" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_FBBA1CA224BD8A3BC542A05CC588B0B9_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_FBBA1CA224BD8A3BC542A05CC588B0B9" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_6AC817F8C9BF272AF1A8A05CC588F5B1" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_FBBA1CA224BD8A3BC542A05CC588B0B9" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_RestrictedStockUnitsRSUMember" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_F2D8F1AD4D285E6FA1DAA05CC5887189" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_FBBA1CA224BD8A3BC542A05CC588B0B9" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_F2D8F1AD4D285E6FA1DAA05CC5887189" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_4EF6EB964E7D271E9664A05CC589DF2B" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_61E0618F683F19AC1AA7A05CC588217C" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_4EF6EB964E7D271E9664A05CC589DF2B" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_6774818CC4A21E1AC3C2A05CC5899103" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_4EF6EB964E7D271E9664A05CC589DF2B" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_6774818CC4A21E1AC3C2A05CC5899103" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_21536732F714C2196437A05CC589FF2B" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_4EF6EB964E7D271E9664A05CC589DF2B" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_21536732F714C2196437A05CC589FF2B" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_084B0D2505F827BBFA03A05CC589FD8E" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_4EF6EB964E7D271E9664A05CC589DF2B" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_084B0D2505F827BBFA03A05CC589FD8E" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_7B2E583665C9C7F5879DA05CC58921DB" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_4EF6EB964E7D271E9664A05CC589DF2B" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_7B2E583665C9C7F5879DA05CC58921DB" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedWeightedAverageGrantDateFairValueAbstract" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedWeightedAverageGrantDateFairValueAbstract_867CAFBC4DA04B29A2EAA05CC5899A23" xlink:type="locator" />
    <definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_4EF6EB964E7D271E9664A05CC589DF2B" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedWeightedAverageGrantDateFairValueAbstract_867CAFBC4DA04B29A2EAA05CC5899A23" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_BD035280D42FF34C65DAA05CC58958CE" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedWeightedAverageGrantDateFairValueAbstract_867CAFBC4DA04B29A2EAA05CC5899A23" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_BD035280D42FF34C65DAA05CC58958CE" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_4D9E8C7EA48491AC770DA05CC5893CAD" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedWeightedAverageGrantDateFairValueAbstract_867CAFBC4DA04B29A2EAA05CC5899A23" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_4D9E8C7EA48491AC770DA05CC5893CAD" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_9133D688ABE73443169AA05CC589B072" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedWeightedAverageGrantDateFairValueAbstract_867CAFBC4DA04B29A2EAA05CC5899A23" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_9133D688ABE73443169AA05CC589B072" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_F0D14F81DF809DB0F283A05CC589E2EC" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedWeightedAverageGrantDateFairValueAbstract_867CAFBC4DA04B29A2EAA05CC5899A23" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_F0D14F81DF809DB0F283A05CC589E2EC" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://www.mistrasgroup.com/role/ShareBasedCompensationShareBasedCompensationTables" xlink:type="extended" />
  <definitionLink xlink:role="http://www.mistrasgroup.com/role/ShareBasedCompensationStockOptionsDetails" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_A5D9BAB0B246BBDF558E6C8157C3AE6A" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_66583EFB14226A2B697C6C8157C34413" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_A5D9BAB0B246BBDF558E6C8157C3AE6A" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_66583EFB14226A2B697C6C8157C34413" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AwardTypeAxis" xlink:label="loc_us-gaap_AwardTypeAxis_353326DBEA9DFA459AEF6C8157C38A68" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_66583EFB14226A2B697C6C8157C34413" xlink:to="loc_us-gaap_AwardTypeAxis_353326DBEA9DFA459AEF6C8157C38A68" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_B51CC0C4F3478F44DC446C8157C325D7_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_353326DBEA9DFA459AEF6C8157C38A68" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_B51CC0C4F3478F44DC446C8157C325D7_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_B51CC0C4F3478F44DC446C8157C325D7" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_353326DBEA9DFA459AEF6C8157C38A68" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_B51CC0C4F3478F44DC446C8157C325D7" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_EmployeeStockOptionMember" xlink:label="loc_us-gaap_EmployeeStockOptionMember_90C2C463EEA255B9A0276C8157C38775" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_B51CC0C4F3478F44DC446C8157C325D7" xlink:to="loc_us-gaap_EmployeeStockOptionMember_90C2C463EEA255B9A0276C8157C38775" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_977DF497FF76924A2C226C8157C3876C" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_A5D9BAB0B246BBDF558E6C8157C3AE6A" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_977DF497FF76924A2C226C8157C3876C" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber_E4F57931A6B0F846328D6C8157C3D1EB" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_977DF497FF76924A2C226C8157C3876C" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber_E4F57931A6B0F846328D6C8157C3D1EB" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross_6E8F90945447655EC0C36C8157C3D966" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_977DF497FF76924A2C226C8157C3876C" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross_6E8F90945447655EC0C36C8157C3D966" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_C3177121472BBF413E896C8157C339B7" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_977DF497FF76924A2C226C8157C3876C" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_C3177121472BBF413E896C8157C339B7" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriod" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriod_88E36D96FD5241AB17DE6C8157C400B1" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_977DF497FF76924A2C226C8157C3876C" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriod_88E36D96FD5241AB17DE6C8157C400B1" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward_9C143C6B977F7DBDAEBC6C8157C432A0" xlink:type="locator" />
    <definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_977DF497FF76924A2C226C8157C3876C" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward_9C143C6B977F7DBDAEBC6C8157C432A0" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice_3D0F0233CAD597BC65F96C8157C45FDB" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward_9C143C6B977F7DBDAEBC6C8157C432A0" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice_3D0F0233CAD597BC65F96C8157C45FDB" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice_6A044A998924629C391E6C8157C414E0" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward_9C143C6B977F7DBDAEBC6C8157C432A0" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice_6A044A998924629C391E6C8157C414E0" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice_4BDEAF43C1F9A391B6876C8157C42EF9" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward_9C143C6B977F7DBDAEBC6C8157C432A0" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice_4BDEAF43C1F9A391B6876C8157C42EF9" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriodWeightedAverageExercisePrice" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriodWeightedAverageExercisePrice_65BEA00BA863BFB056C36C8157C4FF86" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward_9C143C6B977F7DBDAEBC6C8157C432A0" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriodWeightedAverageExercisePrice_65BEA00BA863BFB056C36C8157C4FF86" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedStockOptions" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedStockOptions_6A606A2739B49CF2B4D36C8157C45AA4" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_A5D9BAB0B246BBDF558E6C8157C3AE6A" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedStockOptions_6A606A2739B49CF2B4D36C8157C45AA4" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AllocatedShareBasedCompensationExpense" xlink:label="loc_us-gaap_AllocatedShareBasedCompensationExpense_8242CB42C163D3DFF0056C8157C49A69" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_A5D9BAB0B246BBDF558E6C8157C3AE6A" xlink:to="loc_us-gaap_AllocatedShareBasedCompensationExpense_8242CB42C163D3DFF0056C8157C49A69" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://www.mistrasgroup.com/role/SubsequentEvent" xlink:type="extended" />
  <definitionLink xlink:role="http://www.mistrasgroup.com/role/SubsequentEventDetails" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_SubsequentEventLineItems" xlink:label="loc_us-gaap_SubsequentEventLineItems_9E857E7AC088672CFC1691BFBA093BB2" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_SubsequentEventTable" xlink:label="loc_us-gaap_SubsequentEventTable_418318D3054BA296DB3991BFBA03DE44" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SubsequentEventLineItems_9E857E7AC088672CFC1691BFBA093BB2" xlink:to="loc_us-gaap_SubsequentEventTable_418318D3054BA296DB3991BFBA03DE44" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_SubsequentEventTypeAxis" xlink:label="loc_us-gaap_SubsequentEventTypeAxis_BABFC0313A452E10628E91BFBA03FFD0" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SubsequentEventTable_418318D3054BA296DB3991BFBA03DE44" xlink:to="loc_us-gaap_SubsequentEventTypeAxis_BABFC0313A452E10628E91BFBA03FFD0" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_SubsequentEventTypeDomain" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_AF44A08C2DBA2F31901F91BFBA03ABAB_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_BABFC0313A452E10628E91BFBA03FFD0" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_AF44A08C2DBA2F31901F91BFBA03ABAB_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_SubsequentEventTypeDomain" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_AF44A08C2DBA2F31901F91BFBA03ABAB" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_BABFC0313A452E10628E91BFBA03FFD0" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_AF44A08C2DBA2F31901F91BFBA03ABAB" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_SubsequentEventMember" xlink:label="loc_us-gaap_SubsequentEventMember_A2E9A32051BA3336424391BFBA0389D0" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventTypeDomain_AF44A08C2DBA2F31901F91BFBA03ABAB" xlink:to="loc_us-gaap_SubsequentEventMember_A2E9A32051BA3336424391BFBA0389D0" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_BusinessAcquisitionAxis" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_8F0E0C4B536943659E3E91BFBA03FAF0" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SubsequentEventTable_418318D3054BA296DB3991BFBA03DE44" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_8F0E0C4B536943659E3E91BFBA03FAF0" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_6769E0C9924255D25DE191BFBA04BC46_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_8F0E0C4B536943659E3E91BFBA03FAF0" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_6769E0C9924255D25DE191BFBA04BC46_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_6769E0C9924255D25DE191BFBA04BC46" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_8F0E0C4B536943659E3E91BFBA03FAF0" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_6769E0C9924255D25DE191BFBA04BC46" xlink:type="arc" />
    <loc xlink:href="mg-20160831.xsd#mg_AssetProtectionBusinessMember" xlink:label="loc_mg_AssetProtectionBusinessMember_69B813AF4D4F81BFE83E91BFBA04D1C5" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_6769E0C9924255D25DE191BFBA04BC46" xlink:to="loc_mg_AssetProtectionBusinessMember_69B813AF4D4F81BFE83E91BFBA04D1C5" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_PaymentsToAcquireBusinessesGross" xlink:label="loc_us-gaap_PaymentsToAcquireBusinessesGross_91D47AB105C52C67E25291BFBA098347" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_9E857E7AC088672CFC1691BFBA093BB2" xlink:to="loc_us-gaap_PaymentsToAcquireBusinessesGross_91D47AB105C52C67E25291BFBA098347" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_BusinessCombinationContingentConsiderationArrangementsRangeOfOutcomesValueHigh" xlink:label="loc_us-gaap_BusinessCombinationContingentConsiderationArrangementsRangeOfOutcomesValueHigh_22525312F18A520B0D9E91BFBA09F398" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_9E857E7AC088672CFC1691BFBA093BB2" xlink:to="loc_us-gaap_BusinessCombinationContingentConsiderationArrangementsRangeOfOutcomesValueHigh_22525312F18A520B0D9E91BFBA09F398" xlink:type="arc" />
    <loc xlink:href="mg-20160831.xsd#mg_BusinessCombinationContingentConsiderationPaymentPeriod" xlink:label="loc_mg_BusinessCombinationContingentConsiderationPaymentPeriod_889540650CBB9BEDC68591BFBA092DAE" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_9E857E7AC088672CFC1691BFBA093BB2" xlink:to="loc_mg_BusinessCombinationContingentConsiderationPaymentPeriod_889540650CBB9BEDC68591BFBA092DAE" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://www.mistrasgroup.com/role/UnauditedCondensedConsolidatedStatementsOfCashFlows" xlink:type="extended" />
  <definitionLink xlink:role="http://www.mistrasgroup.com/role/UnauditedCondensedConsolidatedStatementsOfComprehensiveIncome" xlink:type="extended" />
  <definitionLink xlink:role="http://www.mistrasgroup.com/role/UnauditedCondensedConsolidatedStatementsOfIncome" xlink:type="extended" />
</linkbase>
