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Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
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<SEC-DOCUMENT>0001209191-09-057544.txt : 20091217
<SEC-HEADER>0001209191-09-057544.hdr.sgml : 20091217
<ACCEPTANCE-DATETIME>20091217101323
ACCESSION NUMBER:		0001209191-09-057544
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20091215
FILED AS OF DATE:		20091217
DATE AS OF CHANGE:		20091217

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			IDENIX PHARMACEUTICALS INC
		CENTRAL INDEX KEY:			0001093649
		STANDARD INDUSTRIAL CLASSIFICATION:	PHARMACEUTICAL PREPARATIONS [2834]
		IRS NUMBER:				450478605

	BUSINESS ADDRESS:	
		STREET 1:		60 HAMPSHIRE STREET
		STREET 2:		.
		CITY:			CAMBRIDGE
		STATE:			MA
		ZIP:			02139
		BUSINESS PHONE:		(617) 995-9800

	MAIL ADDRESS:	
		STREET 1:		60 HAMPSHIRE STREET
		CITY:			CAMBRIDGE
		STATE:			MA
		ZIP:			02139

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	NOVIRIO PHARMACEUTICALS LTD
		DATE OF NAME CHANGE:	19990820

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			HODGSON THOMAS R
		CENTRAL INDEX KEY:			0001198923
		STANDARD INDUSTRIAL CLASSIFICATION:	FIRE, MARINE & CASUALTY INSURANCE [6331]
		FISCAL YEAR END:			1231

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-49839
		FILM NUMBER:		091246248

	BUSINESS ADDRESS:	
		STREET 1:		385 WASHINGTON ST
		CITY:			SAINT PAUL
		STATE:			MN
		ZIP:			55102
		BUSINESS PHONE:		651-310-6748

	MAIL ADDRESS:	
		STREET 1:		THE TRAVELERS COMPANIES, INC.
		STREET 2:		385 WASHINGTON STREET
		CITY:			ST. PAUL
		STATE:			MN
		ZIP:			55102
</SEC-HEADER>
<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>2009-12-15</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001093649</issuerCik>
        <issuerName>IDENIX PHARMACEUTICALS INC</issuerName>
        <issuerTradingSymbol>IDIX</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001198923</rptOwnerCik>
            <rptOwnerName>HODGSON THOMAS R</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O IDENIX PHARMACEUTICALS, INC.</rptOwnerStreet1>
            <rptOwnerStreet2>60 HAMPSHIRE STREET</rptOwnerStreet2>
            <rptOwnerCity>CAMBRIDGE</rptOwnerCity>
            <rptOwnerState>MA</rptOwnerState>
            <rptOwnerZipCode>02139</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2009-12-15</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>15000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>2.15</value>
                    <footnoteId id="F1"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>46813</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By trust</value>
                    <footnoteId id="F2"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2009-12-16</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>10387</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>2.12</value>
                    <footnoteId id="F3"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>57200</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By trust</value>
                    <footnoteId id="F2"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>35124</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">The price reported in column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $2.13 to $2.16, inclusive. The reporting person undertakes to provide to Idenix Pharmaceuticals, Inc, any secuirty holder of Idenix Pharmaceuticals, Inc., or the staff of the Securities and Exchange Commission upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in footnotes 1 and 3 of this Form 4.</footnote>
        <footnote id="F2">Held by the Thomas R. Hodgson Declaration of Trust.</footnote>
        <footnote id="F3">The price reported in column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $2.07 to $2.18, inclusive.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ John Weidenbruch as attorney-in-fact for Thomas Hodgson</signatureName>
        <signatureDate>2009-12-17</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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