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Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
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MIC-Info: RSA-MD5,RSA,
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<SEC-DOCUMENT>0001250853-10-000045.txt : 20100702
<SEC-HEADER>0001250853-10-000045.hdr.sgml : 20100702
<ACCEPTANCE-DATETIME>20100702124856
ACCESSION NUMBER:		0001250853-10-000045
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20100326
FILED AS OF DATE:		20100702
DATE AS OF CHANGE:		20100702

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			RXI PHARMACEUTICALS CORP
		CENTRAL INDEX KEY:			0001390478
		STANDARD INDUSTRIAL CLASSIFICATION:	PHARMACEUTICAL PREPARATIONS [2834]
		IRS NUMBER:				000000000

	BUSINESS ADDRESS:	
		STREET 1:		60 PRESCOTT  STREET
		CITY:			WORCESTER
		STATE:			MA
		ZIP:			01605
		BUSINESS PHONE:		508-767-3861

	MAIL ADDRESS:	
		STREET 1:		60 PRESCOTT  STREET
		CITY:			WORCESTER
		STATE:			MA
		ZIP:			01605

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			CYTRX CORP
		CENTRAL INDEX KEY:			0000799698
		STANDARD INDUSTRIAL CLASSIFICATION:	BIOLOGICAL PRODUCTS (NO DIAGNOSTIC SUBSTANCES) [2836]
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-33958
		FILM NUMBER:		10934879

	BUSINESS ADDRESS:	
		STREET 1:		11726 SAN VICENTE BOULEVARD
		STREET 2:		SUITE 650
		CITY:			LOS ANGELES
		STATE:			CA
		ZIP:			90049
		BUSINESS PHONE:		310-826-5648

	MAIL ADDRESS:	
		STREET 1:		11726 SAN VICENTE BOULEVARD
		STREET 2:		SUITE 650
		CITY:			LOS ANGELES
		STATE:			CA
		ZIP:			90049
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>primary_doc.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0303</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2010-03-26</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001390478</issuerCik>
        <issuerName>RXI PHARMACEUTICALS CORP</issuerName>
        <issuerTradingSymbol>RXii</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0000799698</rptOwnerCik>
            <rptOwnerName>CYTRX CORP</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>11726 SAN VICENTE BOULEVARD</rptOwnerStreet1>
            <rptOwnerStreet2>SUITE 650</rptOwnerStreet2>
            <rptOwnerCity>LOS ANGELES</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>90049</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2010-03-26</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>675000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>5.7</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>5093881</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <ownerSignature>
        <signatureName>/s/ CytRx Corporation by Steven A. Kriegsman, President &amp; CEO</signatureName>
        <signatureDate>2010-07-01</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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