-----BEGIN PRIVACY-ENHANCED MESSAGE-----
Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
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 TWSM7vrzLADbmYQaionwg5sDW3P6oaM5D3tdezXMm7z1T+B+twIDAQAB
MIC-Info: RSA-MD5,RSA,
 T0OKhb7QlsrYJQpxKb7hGzgeQU2Z1gdEQ5l5QycfVv59UqveC6zw8Uoyv2Z2xloo
 KclJBScYUaAupERmjpAoig==

<SEC-DOCUMENT>0001179110-03-012362.txt : 20031211
<SEC-HEADER>0001179110-03-012362.hdr.sgml : 20031211
<ACCEPTANCE-DATETIME>20031211161507
ACCESSION NUMBER:		0001179110-03-012362
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20031209
FILED AS OF DATE:		20031211

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			ISAACS STEPHEN T
		CENTRAL INDEX KEY:			0001193201

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-21937
		FILM NUMBER:		031049717

	MAIL ADDRESS:	
		STREET 1:		C/O CERUS CORP
		STREET 2:		2411 STENWELL DRIVE
		CITY:			CONCORD
		STATE:			CA
		ZIP:			94520

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			CERUS CORP
		CENTRAL INDEX KEY:			0001020214
		STANDARD INDUSTRIAL CLASSIFICATION:	BIOLOGICAL PRODUCTS (NO DIAGNOSTIC SUBSTANCES) [2836]
		IRS NUMBER:				680262011
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		2411 STANWELL DR
		CITY:			CONCORD
		STATE:			CA
		ZIP:			94520
		BUSINESS PHONE:		9252886000

	MAIL ADDRESS:	
		STREET 1:		2525 STANWELL DRIVE
		STREET 2:		STE 300
		CITY:			CONCORD
		STATE:			CA
		ZIP:			94520

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	CERUS TECHNOLOGIES INC
		DATE OF NAME CHANGE:	19960731
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>edgar.xml
<DESCRIPTION>FORM 4 -
<TEXT>
<XML>
<ownershipDocument>
    <schemaVersion>X0201</schemaVersion>

    <documentType>4</documentType>
<periodOfReport>2003-12-09</periodOfReport>
<notSubjectToSection16>0</notSubjectToSection16>
    <issuer>
        <issuerCik>0001020214</issuerCik>
        <issuerName>CERUS CORP</issuerName>
        <issuerTradingSymbol>CERS</issuerTradingSymbol>
</issuer>
<reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001193201</rptOwnerCik>
            <rptOwnerName>ISAACS STEPHEN T</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O CERUS CORPORATION</rptOwnerStreet1>
            <rptOwnerStreet2>2411 STANWELL DRIVE</rptOwnerStreet2>
            <rptOwnerCity>CONCORD</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>94520</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
            <reportingOwnerRelationship>
<isDirector>1</isDirector>
<isOfficer>1</isOfficer>
<isTenPercentOwner>0</isTenPercentOwner>
<isOther>0</isOther>
<officerTitle>Chief Executive Officer</officerTitle>
<otherText></otherText>
</reportingOwnerRelationship>
</reportingOwner>
<nonDerivativeTable></nonDerivativeTable>
<derivativeTable><derivativeTransaction><securityTitle><value>Option (Right to Buy)</value>
</securityTitle>
<conversionOrExercisePrice><value>4.25</value>
</conversionOrExercisePrice>
<transactionDate><value>2003-12-09</value>
</transactionDate>
<deemedExecutionDate><value>2003-12-09</value>
</deemedExecutionDate>
<transactionCoding><transactionFormType>4</transactionFormType>
<transactionCode>A</transactionCode>
<equitySwapInvolved>0</equitySwapInvolved>
</transactionCoding>
<transactionAmounts><transactionShares><value>45000</value>
</transactionShares>
<transactionPricePerShare><footnoteId id="F2"></footnoteId>
</transactionPricePerShare>
<transactionAcquiredDisposedCode><value>A</value>
</transactionAcquiredDisposedCode>
</transactionAmounts>
<exerciseDate><footnoteId id="F1"></footnoteId>
</exerciseDate>
<expirationDate><value>2013-12-08</value>
</expirationDate>
<underlyingSecurity><underlyingSecurityTitle><value>Common Stock</value>
</underlyingSecurityTitle>
<underlyingSecurityShares><value>45000</value>
</underlyingSecurityShares>
</underlyingSecurity>
<postTransactionAmounts><sharesOwnedFollowingTransaction><value>45000</value>
</sharesOwnedFollowingTransaction>
</postTransactionAmounts>
<ownershipNature><directOrIndirectOwnership><value>D</value>
</directOrIndirectOwnership>
</ownershipNature>
</derivativeTransaction>
</derivativeTable>
<footnotes><footnote id="F1">Option vests monthly over 48 months from November 14, 2003.</footnote>
<footnote id="F2">Not applicable.</footnote>
</footnotes>
<ownerSignature><signatureName>Stephen T. Isaacs by Howard G. Ervin, attorney-in-fact</signatureName>
<signatureDate>2003-12-09</signatureDate>
</ownerSignature>
</ownershipDocument>

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