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  <element name="DefinedContributionPlanAnnualIncrementsVestingPeriod" id="uthr_DefinedContributionPlanAnnualIncrementsVestingPeriod" type="xbrli:integerItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
  <element name="DefinedBenefitPlanEligibilityAge" id="uthr_DefinedBenefitPlanEligibilityAge" type="xbrli:integerItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="instant" />
  <element name="NumberOfMonthsOfSalaryTakenAsGrossBaseForReceiptOfMonthlypayments" id="uthr_NumberOfMonthsOfSalaryTakenAsGrossBaseForReceiptOfMonthlypayments" type="xbrli:integerItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
  <element name="DefinedBenefitPlanVestingPeriod" id="uthr_DefinedBenefitPlanVestingPeriod" type="xbrli:integerItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
  <element name="DefinedBenefitPlanAdditionalNewParticipantsNumber" id="uthr_DefinedBenefitPlanAdditionalNewParticipantsNumber" type="xbrli:integerItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
  <element name="ShareholdersRightsPlanAbstract" id="uthr_ShareholdersRightsPlanAbstract" type="xbrli:stringItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration" />
  <element name="ClassOfWarrantOrRightPurchasePriceOfRightBeforeAmendmentAndRestatement" id="uthr_ClassOfWarrantOrRightPurchasePriceOfRightBeforeAmendmentAndRestatement" type="num:perShareItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="instant" />
  <element name="ClassOfWarrantOrRightPurchasePriceOfRightAfterAmendmentAndRestatement" id="uthr_ClassOfWarrantOrRightPurchasePriceOfRightAfterAmendmentAndRestatement" type="num:perShareItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="instant" />
  <element name="ClassOfWarrantOrRightSharesOfSeriesAJuniorParticipatingPreferredStockPerRight" id="uthr_ClassOfWarrantOrRightSharesOfSeriesAJuniorParticipatingPreferredStockPerRight" type="num:perShareItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="instant" />
  <element name="ClassOfWarrantOrRightConditionOnExerciseOfRightsMinimumPercentageOfCommonStockToBeAcquiredInTenderOffer" id="uthr_ClassOfWarrantOrRightConditionOnExerciseOfRightsMinimumPercentageOfCommonStockToBeAcquiredInTenderOffer" type="num:percentItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="instant" />
  <element name="ScheduleOfDistributionAgreementsTable" id="uthr_ScheduleOfDistributionAgreementsTable" type="xbrli:stringItemType" substitutionGroup="xbrldt:hypercubeItem" abstract="true" nillable="true" xbrli:periodType="duration" />
  <element name="DistributionAgreementsDomain" id="uthr_DistributionAgreementsDomain" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration" />
  <element name="DistributionAgreementsLineItems" id="uthr_DistributionAgreementsLineItems" type="xbrli:stringItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration" />
  <element name="DistributionAgreementsAxis" id="uthr_DistributionAgreementsAxis" type="xbrli:stringItemType" substitutionGroup="xbrldt:dimensionItem" abstract="true" nillable="true" xbrli:periodType="duration" />
  <element name="FairValueByAssetOrLiabilityClassAxis" id="uthr_FairValueByAssetOrLiabilityClassAxis" type="xbrli:stringItemType" substitutionGroup="xbrldt:dimensionItem" abstract="true" nillable="true" xbrli:periodType="duration" />
  <element name="PharmaceuticalRevenueNetMember" id="uthr_PharmaceuticalRevenueNetMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration" />
  <element name="DebtInstrumentAlternativeInterestRateOption" id="uthr_DebtInstrumentAlternativeInterestRateOption" type="num:percentItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
  <element name="DebtInstrumentAlternativeInterestRateOptionSpreadOverFederalFundsEffectiveRate" id="uthr_DebtInstrumentAlternativeInterestRateOptionSpreadOverFederalFundsEffectiveRate" type="num:percentItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
  <element name="DebtInstrumentAlternativeInterestRateOptionBasis" id="uthr_DebtInstrumentAlternativeInterestRateOptionBasis" type="xbrli:stringItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
  <element name="DebtInstrumentAlternativeInterestRateOptionSpread" id="uthr_DebtInstrumentAlternativeInterestRateOptionSpread" type="num:percentItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
  <element name="AccruedRoyaltiesAndRebatesCurrent" id="uthr_AccruedRoyaltiesAndRebatesCurrent" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:balance="credit" xbrli:periodType="instant" />
  <element name="PharmaceuticalMember" id="uthr_PharmaceuticalMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration" />
  <element name="FairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationTableTextBlock" id="uthr_FairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationTableTextBlock" type="nonnum:textBlockItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
  <element name="FairValueByAssetOrLiabilityClassDomain" id="uthr_FairValueByAssetOrLiabilityClassDomain" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration" />
  <element name="FairValueAssetsLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems" id="uthr_FairValueAssetsLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems" type="xbrli:stringItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration" />
  <element name="FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetLiabilityNetValue" id="uthr_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetLiabilityNetValue" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:balance="debit" xbrli:periodType="instant" />
  <element name="FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetLiabilitySettlements" id="uthr_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetLiabilitySettlements" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:balance="credit" xbrli:periodType="duration" />
  <element name="ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfAwardsAvailableForIssuance" id="uthr_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfAwardsAvailableForIssuance" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="instant" />
  <element name="ShareBasedCompensationArrangementByShareBasedPaymentAwardIncreaseInNumberOfAuthorizedSharesAvailableForGrant" id="uthr_ShareBasedCompensationArrangementByShareBasedPaymentAwardIncreaseInNumberOfAuthorizedSharesAvailableForGrant" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="instant" />
  <element name="ShareBasedCompensationArrangementByShareBasedPaymentAwardOtherThanOptionsFairValueAssumptionsRiskFreeInterestRate" id="uthr_ShareBasedCompensationArrangementByShareBasedPaymentAwardOtherThanOptionsFairValueAssumptionsRiskFreeInterestRate" type="num:percentItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
  <element name="ShareBasedCompensationArrangementByShareBasedPaymentAwardOtherThanOptionsFairValueAssumptionsExpectedDividendRate" id="uthr_ShareBasedCompensationArrangementByShareBasedPaymentAwardOtherThanOptionsFairValueAssumptionsExpectedDividendRate" type="num:percentItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
  <element name="ResearchAndDevelopmentObligationWithExtensionOfTerm" id="uthr_ResearchAndDevelopmentObligationWithExtensionOfTerm" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:balance="credit" xbrli:periodType="duration" />
  <element name="AdjustmentsToAdditionalPaidInCapitalConvertibleDebtHedgeAndWarrantsNet" id="uthr_AdjustmentsToAdditionalPaidInCapitalConvertibleDebtHedgeAndWarrantsNet" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:balance="credit" xbrli:periodType="duration" />
  <element name="PaymentsOfConvertibleDebtHedgeAndWarrantsNet" id="uthr_PaymentsOfConvertibleDebtHedgeAndWarrantsNet" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:balance="credit" xbrli:periodType="duration" />
  <element name="ConvertibleNotesDue2011Member" id="uthr_ConvertibleNotesDue2011Member" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration" />
  <element name="ConvertibleNotesDue2016Member" id="uthr_ConvertibleNotesDue2016Member" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration" />
  <element name="DebtInstrumentConversionObligationCommonStockClosingSalesPriceAsPercentageOfConversionPrice" id="uthr_DebtInstrumentConversionObligationCommonStockClosingSalesPriceAsPercentageOfConversionPrice" type="num:percentItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
  <element name="DebtInstrumentConversionObligationCommonStockClosingSalesPriceNumberOfTradingDays" id="uthr_DebtInstrumentConversionObligationCommonStockClosingSalesPriceNumberOfTradingDays" type="xbrli:integerItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
  <element name="DebtInstrumentConversionObligationNumberOfConsecutiveTradingDaysAfterConsecutiveTradingDayPeriod" id="uthr_DebtInstrumentConversionObligationNumberOfConsecutiveTradingDaysAfterConsecutiveTradingDayPeriod" type="xbrli:integerItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
  <element name="DebtInstrumentConversionObligationPeriodOfConsecutiveTradingDays" id="uthr_DebtInstrumentConversionObligationPeriodOfConsecutiveTradingDays" type="xbrli:integerItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
  <element name="DebtInstrumentConversionObligationTradingPriceAsPercentageOfProductOfLastReportedCommonStockSalePriceAndConversionRateMaximum" id="uthr_DebtInstrumentConversionObligationTradingPriceAsPercentageOfProductOfLastReportedCommonStockSalePriceAndConversionRateMaximum" type="num:percentItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
  <element name="RedemptionPriceOfDebtAsPercentageOfPrincipalAmount" id="uthr_RedemptionPriceOfDebtAsPercentageOfPrincipalAmount" type="num:percentItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
  <element name="DebtInstrumentAmortizationPeriod" id="uthr_DebtInstrumentAmortizationPeriod" type="xbrli:integerItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
  <element name="ClassOfWarrantOrRightExcessOfStrikePriceOverInitialConversionPriceAsPercent" id="uthr_ClassOfWarrantOrRightExcessOfStrikePriceOverInitialConversionPriceAsPercent" type="num:percentItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
  <element name="ClassOfWarrantOrRightStrikePriceAsPercentageOfInitialConversionPrice" id="uthr_ClassOfWarrantOrRightStrikePriceAsPercentageOfInitialConversionPrice" type="num:percentItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
  <element name="StockRepurchaseAbstract" id="uthr_StockRepurchaseAbstract" type="xbrli:stringItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration" />
  <element name="PaymentsForRepurchaseOfCommonStockRelatedToInitialShareRepurchase" id="uthr_PaymentsForRepurchaseOfCommonStockRelatedToInitialShareRepurchase" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:balance="debit" xbrli:periodType="duration" />
  <element name="PaymentsForRepurchaseOfCommonStockRelatedToForwardContract" id="uthr_PaymentsForRepurchaseOfCommonStockRelatedToForwardContract" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:balance="debit" xbrli:periodType="duration" />
  <element name="BusinessAcquisitionContingentMilestonePaymentsOnReceivingRegulatoryApprovals" id="uthr_BusinessAcquisitionContingentMilestonePaymentsOnReceivingRegulatoryApprovals" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:balance="credit" xbrli:periodType="instant" />
  <element name="NumberOfShareTrackingAwardsPlans" id="uthr_NumberOfShareTrackingAwardsPlans" type="xbrli:integerItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
  <element name="DefinedBenefitPlanExpectedFutureBenefitPayments" id="uthr_DefinedBenefitPlanExpectedFutureBenefitPayments" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:balance="debit" xbrli:periodType="instant" />
  <element name="RoyaltyPaymentObligationAmount" id="uthr_RoyaltyPaymentObligationAmount" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:balance="credit" xbrli:periodType="duration" />
  <element name="PaymentForAcceleratedShareRepurchaseTransactionCost" id="uthr_PaymentForAcceleratedShareRepurchaseTransactionCost" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:balance="credit" xbrli:periodType="duration" />
  <element name="StockIssuedDuringPeriodValueConversionOfConvertibleSecuritiesAndSharesReceivedThroughHedgeExercise" id="uthr_StockIssuedDuringPeriodValueConversionOfConvertibleSecuritiesAndSharesReceivedThroughHedgeExercise" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:balance="credit" xbrli:periodType="duration" />
  <element name="LicenseCostsIncurredButNotPaid" id="uthr_LicenseCostsIncurredButNotPaid" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:balance="debit" xbrli:periodType="duration" />
  <element name="LossContingencyNumberOfPatentsListedInOrangeBook" id="uthr_LossContingencyNumberOfPatentsListedInOrangeBook" type="xbrli:integerItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
  <element name="LossContingencyNumberOfDaysFromReceiptOfNoticeLetterToCommencePatentInfringementLawsuit" id="uthr_LossContingencyNumberOfDaysFromReceiptOfNoticeLetterToCommencePatentInfringementLawsuit" type="xbrli:integerItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
  <element name="LossContingencyPeriodForWhichLawsuitWouldPrecludeFDAFromApprovingANDA" id="uthr_LossContingencyPeriodForWhichLawsuitWouldPrecludeFDAFromApprovingANDA" type="xbrli:integerItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
  <element name="DosageStrength" id="uthr_DosageStrength" type="xbrli:integerItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
  <element name="ReclassificationPeriodForOperatingResultOfSubsidiary" id="uthr_ReclassificationPeriodForOperatingResultOfSubsidiary" type="xbrli:integerItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
</schema>
