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  <xsd:element id="iclr_ScheduleOfNonCashStockCompensationExpenseTableTextBlock" name="ScheduleOfNonCashStockCompensationExpenseTableTextBlock" nillable="true" substitutionGroup="xbrli:item" type="nonnum:textBlockItemType" xbrli:periodType="duration" />
  <xsd:element id="iclr_ScheduleOfShareBasedCompensationRestrictedStockUnitsPerformanceStockUnitsAwardActivityTableTextBlock" name="ScheduleOfShareBasedCompensationRestrictedStockUnitsPerformanceStockUnitsAwardActivityTableTextBlock" nillable="true" substitutionGroup="xbrli:item" type="nonnum:textBlockItemType" xbrli:periodType="duration" />
  <xsd:element id="iclr_ShareBasedCompensationArrangementByShareBasedPaymentAwardForfeitedInPeriodWeightedAverageGrantDateFairValue" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardForfeitedInPeriodWeightedAverageGrantDateFairValue" nillable="true" substitutionGroup="xbrli:item" type="num:perShareItemType" xbrli:periodType="duration" />
  <xsd:element id="iclr_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonvestedOptionsForfeitedInPeriodWeightedAverageExercisePrice" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardNonvestedOptionsForfeitedInPeriodWeightedAverageExercisePrice" nillable="true" substitutionGroup="xbrli:item" type="num:perShareItemType" xbrli:periodType="duration" />
  <xsd:element id="iclr_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonvestedOptionsGrantedInPeriodWeightedAverageExercisePrice" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardNonvestedOptionsGrantedInPeriodWeightedAverageExercisePrice" nillable="true" substitutionGroup="xbrli:item" type="num:perShareItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="iclr_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonvestedOptionsOutstandingExercisePriceAbstract" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardNonvestedOptionsOutstandingExercisePriceAbstract" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration" />
  <xsd:element id="iclr_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonvestedOptionsOutstandingWeightedAverageExercisePrice" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardNonvestedOptionsOutstandingWeightedAverageExercisePrice" nillable="true" substitutionGroup="xbrli:item" type="num:perShareItemType" xbrli:periodType="instant" />
  <xsd:element id="iclr_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonvestedOptionsVestedInPeriodWeightedAverageExercisePrice" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardNonvestedOptionsVestedInPeriodWeightedAverageExercisePrice" nillable="true" substitutionGroup="xbrli:item" type="num:perShareItemType" xbrli:periodType="duration" />
  <xsd:element id="iclr_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageGrantDateFairValue" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageGrantDateFairValue" nillable="true" substitutionGroup="xbrli:item" type="num:perShareItemType" xbrli:periodType="instant" />
  <xsd:element id="iclr_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisedInPeriodWeightedAverageGrantDateFairValue" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisedInPeriodWeightedAverageGrantDateFairValue" nillable="true" substitutionGroup="xbrli:item" type="num:perShareItemType" xbrli:periodType="duration" />
  <xsd:element id="iclr_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageOptionPrice" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageOptionPrice" nillable="true" substitutionGroup="xbrli:item" type="num:perShareItemType" xbrli:periodType="duration" />
  <xsd:element id="iclr_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingOptionPrice" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingOptionPrice" nillable="true" substitutionGroup="xbrli:item" type="num:perShareItemType" xbrli:periodType="instant" />
  <xsd:element id="iclr_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsWeightedAverageGrantDateFairValue" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsWeightedAverageGrantDateFairValue" nillable="true" substitutionGroup="xbrli:item" type="num:perShareItemType" xbrli:periodType="instant" />
  <xsd:element abstract="true" id="iclr_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsWeightedAverageRemainingContractualTermAbstract" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsWeightedAverageRemainingContractualTermAbstract" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="iclr_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsWeightedAverageGrantDateFairValueAbstract" name="SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsWeightedAverageGrantDateFairValueAbstract" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration" />
  <xsd:element id="iclr_StockRepurchaseProgramAuthorizedPercentage" name="StockRepurchaseProgramAuthorizedPercentage" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="duration" />
  <xsd:element id="iclr_StockholdersEquityAttributabletoParentAndRedeemableNoncontrollingInterestEquityCarryingAmount" name="StockholdersEquityAttributabletoParentAndRedeemableNoncontrollingInterestEquityCarryingAmount" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="instant" />
  <xsd:element abstract="true" id="iclr_TopClientMember" name="TopClientMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="iclr_UnrecognizedTaxBenefitsCurrentYearTaxPositions" name="UnrecognizedTaxBenefitsCurrentYearTaxPositions" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="instant" />
  <xsd:element abstract="true" id="iclr_WorkforceReductionMember" name="WorkforceReductionMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
</xsd:schema>