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Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
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 TWSM7vrzLADbmYQaionwg5sDW3P6oaM5D3tdezXMm7z1T+B+twIDAQAB
MIC-Info: RSA-MD5,RSA,
 ElGXPE4U3W4/rmY70kvKRN1lk2ol24KbOzZdxaoD/wyANPA6W1cSUjM2Qa2F36Db
 A/0sCxvSECyLCA3gv5cvuA==

<SEC-DOCUMENT>0001082554-05-000154.txt : 20051227
<SEC-HEADER>0001082554-05-000154.hdr.sgml : 20051226
<ACCEPTANCE-DATETIME>20051227161324
ACCESSION NUMBER:		0001082554-05-000154
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20051222
FILED AS OF DATE:		20051227
DATE AS OF CHANGE:		20051227

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			ROTHBLATT MARTINE A
		CENTRAL INDEX KEY:			0001106578

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-26301
		FILM NUMBER:		051287166

	BUSINESS ADDRESS:	
		STREET 1:		1110 SPRING STREET
		CITY:			SILVER SPRING
		STATE:			MD
		ZIP:			20910
		BUSINESS PHONE:		3016089292

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			UNITED THERAPEUTICS CORP
		CENTRAL INDEX KEY:			0001082554
		STANDARD INDUSTRIAL CLASSIFICATION:	PHARMACEUTICAL PREPARATIONS [2834]
		IRS NUMBER:				521984749
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		1110 SPRING ST
		CITY:			SILVER SPRING
		STATE:			MD
		ZIP:			20910
		BUSINESS PHONE:		3016089292

	MAIL ADDRESS:	
		STREET 1:		1110 SPRING ST
		CITY:			SILVER SPRING
		STATE:			MD
		ZIP:			20910
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>primary_doc.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0202</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2005-12-22</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001082554</issuerCik>
        <issuerName>UNITED THERAPEUTICS CORP</issuerName>
        <issuerTradingSymbol>UTHR</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001106578</rptOwnerCik>
            <rptOwnerName>ROTHBLATT MARTINE A</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1></rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity></rptOwnerCity>
            <rptOwnerState></rptOwnerState>
            <rptOwnerZipCode></rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>CEO</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2005-12-22</value>
            </transactionDate>
            <deemedExecutionDate>
                <value>2005-12-22</value>
            </deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>5000</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>72.2069</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>303368</value>
                    <footnoteId id="F2"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">This sale of 5,000 shares is pursuant to the 10b5-1 Plan adopted by the reporting person on August 19, 2002.</footnote>
        <footnote id="F2">Includes 62,173 shares held by the reporting person's spouse.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ Paul A. Mahon under Power of Attorney</signatureName>
        <signatureDate>2005-12-27</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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