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Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
Originator-Key-Asymmetric:
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 TWSM7vrzLADbmYQaionwg5sDW3P6oaM5D3tdezXMm7z1T+B+twIDAQAB
MIC-Info: RSA-MD5,RSA,
 AgibvJZonPQXaypIgmnjzdyHO1cWRH1ZoOtqmWkrWjebYzKdZ7kHYMCVle8fWnnY
 LETgI6e4pc4vfmfgObjCeA==

<SEC-DOCUMENT>0001179110-05-000572.txt : 20050105
<SEC-HEADER>0001179110-05-000572.hdr.sgml : 20050105
<ACCEPTANCE-DATETIME>20050105171953
ACCESSION NUMBER:		0001179110-05-000572
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20050103
FILED AS OF DATE:		20050105
DATE AS OF CHANGE:		20050105

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			CATLIN AVERY W
		CENTRAL INDEX KEY:			0001255348

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-15006
		FILM NUMBER:		05513592

	MAIL ADDRESS:	
		STREET 1:		241 CENTRAL STREET
		CITY:			HINGHAM
		STATE:			MA
		ZIP:			02043

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			AVANT IMMUNOTHERAPEUTICS INC
		CENTRAL INDEX KEY:			0000744218
		STANDARD INDUSTRIAL CLASSIFICATION:	IN VITRO & IN VIVO DIAGNOSTIC SUBSTANCES [2835]
		IRS NUMBER:				133191702
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		119 FOURTH AVE
		CITY:			NEEDHAM
		STATE:			MA
		ZIP:			02494
		BUSINESS PHONE:		7814330771

	MAIL ADDRESS:	
		STREET 1:		119 FOURTH AVE
		CITY:			NEEDHAM
		STATE:			MA
		ZIP:			021942725

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	T CELL SCIENCES INC
		DATE OF NAME CHANGE:	19920703
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>edgar.xml
<DESCRIPTION>FORM 4 -
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0202</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2005-01-03</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000744218</issuerCik>
        <issuerName>AVANT IMMUNOTHERAPEUTICS INC</issuerName>
        <issuerTradingSymbol>AVAN</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001255348</rptOwnerCik>
            <rptOwnerName>CATLIN AVERY W</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>241 CENTRAL STREET</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>HINGHAM</rptOwnerCity>
            <rptOwnerState>MA</rptOwnerState>
            <rptOwnerZipCode>02043</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Sr. VP &amp; CFO</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable></nonDerivativeTable>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Incentive Stock Option</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>2.075</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2005-01-03</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>12000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>2.075</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <value>2009-01-03</value>
            </exerciseDate>
            <expirationDate>
                <value>2015-01-03</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>12000</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>259000</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes></footnotes>

    <ownerSignature>
        <signatureName>Avery W. Catlin</signatureName>
        <signatureDate>2005-01-05</signatureDate>
    </ownerSignature>
</ownershipDocument>

</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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