<SEC-DOCUMENT>0001288123-15-000039.txt : 20150929
<SEC-HEADER>0001288123-15-000039.hdr.sgml : 20150929
<ACCEPTANCE-DATETIME>20150929201927
ACCESSION NUMBER:		0001288123-15-000039
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20150925
FILED AS OF DATE:		20150929
DATE AS OF CHANGE:		20150929

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			AGENUS INC
		CENTRAL INDEX KEY:			0001098972
		STANDARD INDUSTRIAL CLASSIFICATION:	BIOLOGICAL PRODUCTS (NO DIAGNOSTIC SUBSTANCES) [2836]
		IRS NUMBER:				061562417
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		3 FORBES ROAD
		CITY:			LEXINGTON
		STATE:			MA
		ZIP:			02421
		BUSINESS PHONE:		781-674-4410

	MAIL ADDRESS:	
		STREET 1:		3 FORBES ROAD
		CITY:			LEXINGTON
		STATE:			MA
		ZIP:			02421

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	ANTIGENICS INC /DE/
		DATE OF NAME CHANGE:	19991115

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Ballantyne Charles Evan
		CENTRAL INDEX KEY:			0001371742

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-29089
		FILM NUMBER:		151132007

	MAIL ADDRESS:	
		STREET 1:		27 HEARTHSTONE ROAD
		CITY:			HOPKINTON
		STATE:			MA
		ZIP:			01748
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>wf-form4_144357235723480.xml
<DESCRIPTION>FORM 4
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2015-09-25</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001098972</issuerCik>
        <issuerName>AGENUS INC</issuerName>
        <issuerTradingSymbol>AGEN</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001371742</rptOwnerCik>
            <rptOwnerName>Ballantyne Charles Evan</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O AGENUS INC.</rptOwnerStreet1>
            <rptOwnerStreet2>3 FORBES ROAD</rptOwnerStreet2>
            <rptOwnerCity>LEXINGTON</rptOwnerCity>
            <rptOwnerState>MA</rptOwnerState>
            <rptOwnerZipCode>02421</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Chief Financial Officer</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Commmon Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2015-09-25</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>10000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>5.05</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>10000</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes></footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>Christine M. Klaskin, by Power of Attorney</signatureName>
        <signatureDate>2015-09-29</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
