<SUBMISSION>
<ACCESSION-NUMBER>0001209191-09-003961
<TYPE>4
<PUBLIC-DOCUMENT-COUNT>1
<PERIOD>20090115
<FILING-DATE>20090120
<DATE-OF-FILING-DATE-CHANGE>20090120
<REPORTING-OWNER>
<OWNER-DATA>
<CONFORMED-NAME>Andrikopoulos Konstantinos
<CIK>0001449992
</OWNER-DATA>
<FILING-VALUES>
<FORM-TYPE>4
<ACT>34
<FILE-NUMBER>001-33958
<FILM-NUMBER>09535546
</FILING-VALUES>
<BUSINESS-ADDRESS>
<PHONE>508-929-3612
</BUSINESS-ADDRESS>
<MAIL-ADDRESS>
<STREET1>60 PRESCOTT STREET
<CITY>WORCESTER
<STATE>MA
<ZIP>01605
</MAIL-ADDRESS>
</REPORTING-OWNER>
<ISSUER>
<COMPANY-DATA>
<CONFORMED-NAME>RXI PHARMACEUTICALS CORP
<CIK>0001390478
<ASSIGNED-SIC>2834
<IRS-NUMBER>000000000
</COMPANY-DATA>
<BUSINESS-ADDRESS>
<STREET1>60 PRESCOTT  STREET
<CITY>WORCESTER
<STATE>MA
<ZIP>01605
<PHONE>508-767-3861
</BUSINESS-ADDRESS>
<MAIL-ADDRESS>
<STREET1>60 PRESCOTT  STREET
<CITY>WORCESTER
<STATE>MA
<ZIP>01605
</MAIL-ADDRESS>
</ISSUER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>doc4.xml
<DESCRIPTION>FORM 4 SUBMISSION
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0303</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2009-01-15</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

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

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001449992</rptOwnerCik>
            <rptOwnerName>Andrikopoulos Konstantinos</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>60 PRESCOTT STREET</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>WORCESTER</rptOwnerCity>
            <rptOwnerState>MA</rptOwnerState>
            <rptOwnerZipCode>01605</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>VP, Legal</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Stock Option</value>
                <footnoteId id="F1"/>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>4.19</value>
                <footnoteId id="F2"/>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2009-01-15</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>100000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0.00</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F3"/>
            </exerciseDate>
            <expirationDate>
                <value>2019-01-15</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>100000</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>100000</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Granted pursuant to the RXi Pharmaceuticals Corporation 2007 Incentive Plan.</footnote>
        <footnote id="F2">Per share.</footnote>
        <footnote id="F3">6,250 of the options will vest on February 10, 2009 and the remaining shares will vest in equal installments on each of the next 15 quarterly anniversaries beginning on July 10, 2009.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ Konstantinos Andrikopoulos</signatureName>
        <signatureDate>2009-01-20</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SUBMISSION>
