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  <xs:element id="regn_CollaborationandContractManufacturingMember" abstract="true" name="CollaborationandContractManufacturingMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="regn_AcquiredInProcessResearchAndDevelopment" abstract="false" name="AcquiredInProcessResearchAndDevelopment" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="regn_StockIssuedDistributedDuringPeriodSharesEmployeeBenefitPlan" abstract="false" name="StockIssuedDistributedDuringPeriodSharesEmployeeBenefitPlan" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:sharesItemType"/>
  <xs:element id="regn_StockIssuedDistributedDuringPeriodValueEmployeeBenefitPlan" abstract="false" name="StockIssuedDistributedDuringPeriodValueEmployeeBenefitPlan" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="regn_MarketableAndOtherSecuritiesGainLoss" abstract="false" name="MarketableAndOtherSecuritiesGainLoss" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="regn_AcquiredInProcessResearchAndDevelopmentAssetAcquisition" abstract="false" name="AcquiredInProcessResearchAndDevelopmentAssetAcquisition" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="regn_PaymentsToAcquireIntangibleAssets1" abstract="false" name="PaymentsToAcquireIntangibleAssets1" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="regn_ScheduleOfSalesRelatedDeductionsActivityTableTextBlock" abstract="false" name="ScheduleOfSalesRelatedDeductionsActivityTableTextBlock" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:textBlockItemType"/>
  <xs:element id="regn_AssetsAndLiabilitiesLesseeTableTextBlock" abstract="false" name="AssetsAndLiabilitiesLesseeTableTextBlock" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:textBlockItemType"/>
  <xs:element id="regn_TwoIndividualCustomersMember" abstract="true" name="TwoIndividualCustomersMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="regn_ReportableSegmentMember" abstract="true" name="ReportableSegmentMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="regn_ResearchAndDevelopmentExpenseTypeAxis" abstract="true" name="ResearchAndDevelopmentExpenseTypeAxis" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrldt:dimensionItem" type="xbrli:stringItemType"/>
  <xs:element id="regn_ResearchAndDevelopmentExpenseTypeDomain" abstract="true" name="ResearchAndDevelopmentExpenseTypeDomain" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="regn_DirectExpenseMember" abstract="true" name="DirectExpenseMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="regn_IndirectExpenseMember" abstract="true" name="IndirectExpenseMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="regn_PayrollAndBenefitsMember" abstract="true" name="PayrollAndBenefitsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="regn_LabSuppliesAndOtherResearchAndDevelopmentCostsMember" abstract="true" name="LabSuppliesAndOtherResearchAndDevelopmentCostsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="regn_OccupancyAndOtherOperatingCostsMember" abstract="true" name="OccupancyAndOtherOperatingCostsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="regn_ClinicalAndManufacturingCostsMember" abstract="true" name="ClinicalAndManufacturingCostsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="regn_ResearchAndDevelopmentExpenseReimbursements" abstract="false" name="ResearchAndDevelopmentExpenseReimbursements" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="regn_ELYEAHDAndEYLEAMember" abstract="true" name="ELYEAHDAndEYLEAMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="regn_ELYEAHDMember" abstract="true" name="ELYEAHDMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="regn_EyleaNetProductSalesMember" abstract="true" name="EyleaNetProductSalesMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="regn_LIBTAYONetProductSalesMember" abstract="true" name="LIBTAYONetProductSalesMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="regn_PraluentNetProductSalesMember" abstract="true" name="PraluentNetProductSalesMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="regn_EvkeezaMember" abstract="true" name="EvkeezaMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="regn_InmazebMember" abstract="true" name="InmazebMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="regn_GrossProductRevenueMember" abstract="true" name="GrossProductRevenueMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="regn_BesseMedicalMember" abstract="true" name="BesseMedicalMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="regn_McKessonCorporationMember" abstract="true" name="McKessonCorporationMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="regn_RebatesChargebacksAndDiscountsMember" abstract="true" name="RebatesChargebacksAndDiscountsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="regn_DistributionRelatedFeesMember" abstract="true" name="DistributionRelatedFeesMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="regn_OtherSalesRelatedDeductionsMember" abstract="true" name="OtherSalesRelatedDeductionsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="regn_SanofiCollaborationAgreementAntibodyMember" abstract="true" name="SanofiCollaborationAgreementAntibodyMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="regn_SanofiCollaborationAgreementImmunooncologyMember" abstract="true" name="SanofiCollaborationAgreementImmunooncologyMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="regn_CostOfGoodsSoldMember" abstract="true" name="CostOfGoodsSoldMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="regn_ShareOfProfitLossesMember" abstract="true" name="ShareOfProfitLossesMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="regn_SalesBasedMilestoneEarnedMember" abstract="true" name="SalesBasedMilestoneEarnedMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="regn_ReimbursementForManufacturingOfCommercialSuppliesMember" abstract="true" name="ReimbursementForManufacturingOfCommercialSuppliesMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="regn_OtherCollaborationAgreementsMember" abstract="true" name="OtherCollaborationAgreementsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="regn_ReimbursementOfResearchAndDevelopmentExpensesNetOfObligationForShareOfRDExpensesMember" abstract="true" name="ReimbursementOfResearchAndDevelopmentExpensesNetOfObligationForShareOfRDExpensesMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="regn_ReimbursementOfCommercializationRelatedExpensesMember" abstract="true" name="ReimbursementOfCommercializationRelatedExpensesMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="regn_ReimbursementOfResearchAndDevelopmentExpensesMember" abstract="true" name="ReimbursementOfResearchAndDevelopmentExpensesMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="regn_SanofisShareOfLibtayoUSGrossProfitsMember" abstract="true" name="SanofisShareOfLibtayoUSGrossProfitsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="regn_AmountsRecognizedInConnectionWithUpFrontPaymentsMember" abstract="true" name="AmountsRecognizedInConnectionWithUpFrontPaymentsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="regn_PaymentToCollaboratingParty" abstract="false" name="PaymentToCollaboratingParty" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="regn_SalesMilestonesAxis" abstract="true" name="SalesMilestonesAxis" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrldt:dimensionItem" type="xbrli:stringItemType"/>
  <xs:element id="regn_SalesMilestonesDomain" abstract="true" name="SalesMilestonesDomain" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="regn_SalesMilestoneFiveMember" abstract="true" name="SalesMilestoneFiveMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="regn_SalesMilestoneThreeMember" abstract="true" name="SalesMilestoneThreeMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="regn_SalesMilestoneFourMember" abstract="true" name="SalesMilestoneFourMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="regn_PercentageOfTrialCostsRequiredToBeFundedByCollaboratingParty" abstract="false" name="PercentageOfTrialCostsRequiredToBeFundedByCollaboratingParty" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:percentItemType"/>
  <xs:element id="regn_PercentageOfQuarterlyProfitsRequiredToBePaidForReimbursementOfDevelopmentCosts" abstract="false" name="PercentageOfQuarterlyProfitsRequiredToBePaidForReimbursementOfDevelopmentCosts" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:percentItemType"/>
  <xs:element id="regn_PercentageOfShareOfProfitsUsedToReimburseCollaboratingPartyForTrialCosts" abstract="false" name="PercentageOfShareOfProfitsUsedToReimburseCollaboratingPartyForTrialCosts" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:percentItemType"/>
  <xs:element id="regn_ContingentReimbursementObligation" abstract="false" name="ContingentReimbursementObligation" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="regn_StartingShareOfProfitsOutsideUnitedStatesBasedOnSalesForCollaboratingParty" abstract="false" name="StartingShareOfProfitsOutsideUnitedStatesBasedOnSalesForCollaboratingParty" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:percentItemType"/>
  <xs:element id="regn_StartingShareOfProfitsOutsideUnitedStatesBasedOnSalesForCompany" abstract="false" name="StartingShareOfProfitsOutsideUnitedStatesBasedOnSalesForCompany" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:percentItemType"/>
  <xs:element id="regn_EndingShareOfProfitsOutsideUnitedStatesBasedOnSalesForCollaboratingParty" abstract="false" name="EndingShareOfProfitsOutsideUnitedStatesBasedOnSalesForCollaboratingParty" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:percentItemType"/>
  <xs:element id="regn_EndingShareOfProfitsOutsideUnitedStatesBasedOnSalesForCompany" abstract="false" name="EndingShareOfProfitsOutsideUnitedStatesBasedOnSalesForCompany" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:percentItemType"/>
  <xs:element id="regn_RevenueRemainingPerformanceObligationVariableConsiderationAmount" abstract="false" name="RevenueRemainingPerformanceObligationVariableConsiderationAmount" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="regn_Levelsoftwelvemonthsalesatwhichsalesmilestonepaymentswouldbereceived" abstract="false" name="Levelsoftwelvemonthsalesatwhichsalesmilestonepaymentswouldbereceived" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="regn_PeriodForAchievingSalesTargetForMilestonePaymentRollingBasis" abstract="false" name="PeriodForAchievingSalesTargetForMilestonePaymentRollingBasis" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:durationItemType"/>
  <xs:element id="regn_NumberOfSalesBasedMilestones" abstract="false" name="NumberOfSalesBasedMilestones" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:integerItemType"/>
  <xs:element id="regn_SanofiMember" abstract="true" name="SanofiMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="regn_RegulatoryMilestoneMember" abstract="true" name="RegulatoryMilestoneMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="regn_SalesBasedMilestoneOneMember" abstract="true" name="SalesBasedMilestoneOneMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="regn_SalesBasedMilestoneTwoMember" abstract="true" name="SalesBasedMilestoneTwoMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="regn_MilestoneTypeAxis" abstract="true" name="MilestoneTypeAxis" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrldt:dimensionItem" type="xbrli:stringItemType"/>
  <xs:element id="regn_MilestoneTypeDomain" abstract="true" name="MilestoneTypeDomain" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="regn_SalesBasedMilestonesMember" abstract="true" name="SalesBasedMilestonesMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="regn_UpFrontPaymentToCollaboratingParty" abstract="false" name="UpFrontPaymentToCollaboratingParty" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="regn_RoyaltyPaymentToCollaboratingPartyPercentageOfNetProductSales" abstract="false" name="RoyaltyPaymentToCollaboratingPartyPercentageOfNetProductSales" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:percentItemType"/>
  <xs:element id="regn_BayerCollaborationAgreementMember" abstract="true" name="BayerCollaborationAgreementMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="regn_PercentageOfRepaymentOfDevelopmentBalanceOutOfProfits" abstract="false" name="PercentageOfRepaymentOfDevelopmentBalanceOutOfProfits" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:percentItemType"/>
  <xs:element id="regn_ResearchAndDevelopmentExpensesAndReductionOfResearchAndDevelopmentExpenseMember" abstract="true" name="ResearchAndDevelopmentExpensesAndReductionOfResearchAndDevelopmentExpenseMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="regn_OneTimePaymentInConnectionWithChangeInJapanArrangementMember" abstract="true" name="OneTimePaymentInConnectionWithChangeInJapanArrangementMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="regn_RegeneronsObligationOfResearchAndDevelopmentExpensesNetOfReimbursementOfResearchAndDevelopmentExpensesMember" abstract="true" name="RegeneronsObligationOfResearchAndDevelopmentExpensesNetOfReimbursementOfResearchAndDevelopmentExpensesMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="regn_RocheCollaborationAgreementMember" abstract="true" name="RocheCollaborationAgreementMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="regn_OtherMember" abstract="true" name="OtherMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="regn_ThroughDecember312023Member" abstract="true" name="ThroughDecember312023Member" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="regn_January12024ThroughDecember312026Member" abstract="true" name="January12024ThroughDecember312026Member" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="regn_SonomaBiotherapeuticsIncMember" abstract="true" name="SonomaBiotherapeuticsIncMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="regn_AlnylamPharmaceuticalsIncMember" abstract="true" name="AlnylamPharmaceuticalsIncMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="regn_IntelliaTherapeuticsInc.Member" abstract="true" name="IntelliaTherapeuticsInc.Member" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="regn_CheckmatePharmaceuticalsIncMember" abstract="true" name="CheckmatePharmaceuticalsIncMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="regn_RoyaltyRateMinimum" abstract="false" name="RoyaltyRateMinimum" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:percentItemType"/>
  <xs:element id="regn_RoyaltyRateMaximum" abstract="false" name="RoyaltyRateMaximum" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:percentItemType"/>
  <xs:element id="regn_PaymentsForRoyaltiesPercentage" abstract="false" name="PaymentsForRoyaltiesPercentage" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:percentItemType"/>
  <xs:element id="regn_DebtSecuritiesAvailableForSaleFairValueMaturityAllocatedAndSingleMaturityDateAfterYear5" abstract="false" name="DebtSecuritiesAvailableForSaleFairValueMaturityAllocatedAndSingleMaturityDateAfterYear5" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="regn_ClassificationOfInvestmentAxis" abstract="true" name="ClassificationOfInvestmentAxis" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrldt:dimensionItem" type="xbrli:stringItemType"/>
  <xs:element id="regn_ClassificationOfInvestmentDomain" abstract="true" name="ClassificationOfInvestmentDomain" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="regn_UnrestrictedMember" abstract="true" name="UnrestrictedMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="regn_RestrictedMember" abstract="true" name="RestrictedMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="regn_ComputerEquipmentAndSoftwareMember" abstract="true" name="ComputerEquipmentAndSoftwareMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="regn_FurnitureOfficeEquipmentAndOtherMember" abstract="true" name="FurnitureOfficeEquipmentAndOtherMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="regn_DepreciationDepletionAndAmortizationExcludingIntangibleAssets" abstract="false" name="DepreciationDepletionAndAmortizationExcludingIntangibleAssets" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="regn_ProductRightsMember" abstract="true" name="ProductRightsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="regn_AccruedClinicalTrialExpenseCurrent" abstract="false" name="AccruedClinicalTrialExpenseCurrent" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="regn_AccrualForSalesRelatedCostsCurrent" abstract="false" name="AccrualForSalesRelatedCostsCurrent" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="regn_SeniorUnsecuredNotesDue2030Member" abstract="true" name="SeniorUnsecuredNotesDue2030Member" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="regn_SeniorUnsecuredNotesDue2050Member" abstract="true" name="SeniorUnsecuredNotesDue2050Member" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="regn_LineOfCreditFacilityIncreaseLimit" abstract="false" name="LineOfCreditFacilityIncreaseLimit" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="regn_LaboratoryAndOfficeFacilitiesMember" abstract="true" name="LaboratoryAndOfficeFacilitiesMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="regn_LeaseRightofUseAsset" abstract="false" name="LeaseRightofUseAsset" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="regn_LeaseLiability" abstract="false" name="LeaseLiability" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="regn_OperatingLeaseRightOfUseAssetAccumulatedAmortization" abstract="false" name="OperatingLeaseRightOfUseAssetAccumulatedAmortization" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="regn_FinanceLeaseCost" abstract="false" name="FinanceLeaseCost" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="regn_LeaseTermAbstract" abstract="true" name="LeaseTermAbstract" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:stringItemType"/>
  <xs:element id="regn_LeaseDiscountRateAbstract" abstract="true" name="LeaseDiscountRateAbstract" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:stringItemType"/>
  <xs:element id="regn_LeaseLiabilityPaymentDueAbstractAbstract" abstract="true" name="LeaseLiabilityPaymentDueAbstractAbstract" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:stringItemType"/>
  <xs:element id="regn_LeaseLiabilityToBePaidYearOne" abstract="false" name="LeaseLiabilityToBePaidYearOne" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="regn_LeaseLiabilityToBePaidYearTwo" abstract="false" name="LeaseLiabilityToBePaidYearTwo" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="regn_LeaseLiabilityToBePaidYearThree" abstract="false" name="LeaseLiabilityToBePaidYearThree" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="regn_LeaseLiabilityToBePaidYearFour" abstract="false" name="LeaseLiabilityToBePaidYearFour" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="regn_LeaseLiabilityToBePaidYearFive" abstract="false" name="LeaseLiabilityToBePaidYearFive" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="regn_LeaseLiabilityToBePaidAfterYearFive" abstract="false" name="LeaseLiabilityToBePaidAfterYearFive" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="regn_LeaseLiabilityPaymentsDue" abstract="false" name="LeaseLiabilityPaymentsDue" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="regn_LeaseLiabilityUndiscountedExcessAmount" abstract="false" name="LeaseLiabilityUndiscountedExcessAmount" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="regn_ShareRepurchaseProgramNovember2021Member" abstract="true" name="ShareRepurchaseProgramNovember2021Member" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="regn_ShareRepurchaseProgramJanuary2023Member" abstract="true" name="ShareRepurchaseProgramJanuary2023Member" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="regn_ShareRepurchaseProgramApril2024Member" abstract="true" name="ShareRepurchaseProgramApril2024Member" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="regn_ShareRepurchaseProgramFebruary2025Member" abstract="true" name="ShareRepurchaseProgramFebruary2025Member" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="regn_NumberOfVotesPerShare" abstract="false" name="NumberOfVotesPerShare" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:integerItemType"/>
  <xs:element id="regn_ShareRepurchaseProgramsMember" abstract="true" name="ShareRepurchaseProgramsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="regn_AmendedRestatedLongTermIncentivePlan2014Member" abstract="true" name="AmendedRestatedLongTermIncentivePlan2014Member" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="regn_NonPerformanceBasedStockOptionsMember" abstract="true" name="NonPerformanceBasedStockOptionsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="regn_ShareBasedCompensationArrangementByShareBasedPaymentAwardExpiration" abstract="false" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardExpiration" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:durationItemType"/>
  <xs:element id="regn_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsCancelledInPeriod" abstract="false" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsCancelledInPeriod" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:sharesItemType"/>
  <xs:element id="regn_DeferredTaxAssetsCapitalizedResearchAndDevelopmentExpenses" abstract="false" name="DeferredTaxAssetsCapitalizedResearchAndDevelopmentExpenses" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="regn_UnrecognizedTaxBenefitsDecreaseResultingFromSettlementsWithTaxingAuthoritiesAndReductionResultingFromLapseOfApplicableStatuteOfLimitations" abstract="false" name="UnrecognizedTaxBenefitsDecreaseResultingFromSettlementsWithTaxingAuthoritiesAndReductionResultingFromLapseOfApplicableStatuteOfLimitations" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="regn_A631PatentMember" abstract="true" name="A631PatentMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="regn_NumberOfInterPartiesReviewIPRPetitionsFiled" abstract="false" name="NumberOfInterPartiesReviewIPRPetitionsFiled" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:integerItemType"/>
  <xs:element id="regn_NumberOfShareholderDerivativeComplaintsFiled" abstract="false" name="NumberOfShareholderDerivativeComplaintsFiled" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:integerItemType"/>
  <xs:element id="regn_AcquisitionsContingentConsiderationAccruedButNotYetPaid" abstract="false" name="AcquisitionsContingentConsiderationAccruedButNotYetPaid" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="regn_KathrynGuariniPh.D.Member" abstract="true" name="KathrynGuariniPh.D.Member" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
</xs:schema>
