<SUBMISSION>
<ACCESSION-NUMBER>0001179110-09-005777
<TYPE>3/A
<PUBLIC-DOCUMENT-COUNT>2
<PERIOD>20090318
<FILING-DATE>20090331
<DATE-OF-FILING-DATE-CHANGE>20090331
<REPORTING-OWNER>
<OWNER-DATA>
<CONFORMED-NAME>Green Kevin Dennis
<CIK>0001459351
</OWNER-DATA>
<FILING-VALUES>
<FORM-TYPE>3/A
<ACT>34
<FILE-NUMBER>000-21937
<FILM-NUMBER>09720810
</FILING-VALUES>
<MAIL-ADDRESS>
<STREET1>C/O CERUS CORPORATION
<STREET2>2411 STANWELL DRIVE
<CITY>CONCORD
<STATE>CA
<ZIP>94520
</MAIL-ADDRESS>
</REPORTING-OWNER>
<ISSUER>
<COMPANY-DATA>
<CONFORMED-NAME>CERUS CORP
<CIK>0001020214
<ASSIGNED-SIC>3841
<IRS-NUMBER>680262011
<STATE-OF-INCORPORATION>DE
<FISCAL-YEAR-END>1231
</COMPANY-DATA>
<BUSINESS-ADDRESS>
<STREET1>2411 STANWELL DR
<CITY>CONCORD
<STATE>CA
<ZIP>94520
<PHONE>9252886000
</BUSINESS-ADDRESS>
<MAIL-ADDRESS>
<STREET1>2525 STANWELL DRIVE
<STREET2>STE 300
<CITY>CONCORD
<STATE>CA
<ZIP>94520
</MAIL-ADDRESS>
<FORMER-COMPANY>
<FORMER-CONFORMED-NAME>CERUS TECHNOLOGIES INC
<DATE-CHANGED>19960731
</FORMER-COMPANY>
</ISSUER>
<DOCUMENT>
<TYPE>3/A
<SEQUENCE>1
<FILENAME>edgar.xml
<DESCRIPTION>FORM 3/A -
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0203</schemaVersion>

    <documentType>3/A</documentType>

    <periodOfReport>2009-03-18</periodOfReport>

    <dateOfOriginalSubmission>2009-03-26</dateOfOriginalSubmission>

    <noSecuritiesOwned>0</noSecuritiesOwned>

    <issuer>
        <issuerCik>0001020214</issuerCik>
        <issuerName>CERUS CORP</issuerName>
        <issuerTradingSymbol>CERS</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001459351</rptOwnerCik>
            <rptOwnerName>Green Kevin Dennis</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>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Chief Accounting Officer</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>14871</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <derivativeTable>
        <derivativeHolding>
            <securityTitle>
                <value>Option (Right to Buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>10.15</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <footnoteId id="F1"/>
            </exerciseDate>
            <expirationDate>
                <value>2016-01-02</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>25000</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>Option (Right to Buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>5.55</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <footnoteId id="F2"/>
            </exerciseDate>
            <expirationDate>
                <value>2016-10-01</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>6150</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>Optioin (Right to Buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>8.73</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <footnoteId id="F3"/>
            </exerciseDate>
            <expirationDate>
                <value>2017-09-30</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>7500</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>Option (Right to Buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>4.19</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <footnoteId id="F4"/>
            </exerciseDate>
            <expirationDate>
                <value>2018-09-30</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>11000</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>Option (Right to Buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>0.79</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <footnoteId id="F5"/>
            </exerciseDate>
            <expirationDate>
                <value>2019-01-11</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>23000</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">One eighth (1/8th) of the shares subject to the Option shall vest six (6) months after January 3, 2006, and one forty-eighth (1/48th) of the shares subject to the Option shall vest on the first day of each month thereafter.</footnote>
        <footnote id="F2">The shares subject to the Option shall vest in forty-eight (48) equal monthly installments over 4 years after October 2, 2006.</footnote>
        <footnote id="F3">One eighth (1/8th) of the shares subject to the Option shall vest six (6) months after October 1, 2007, and one forty-eighth (1/48th) of the shares subject to the Option shall vest on the first day of each month thereafter.</footnote>
        <footnote id="F4">One eighth (1/8th) of the shares subject to the Option shall vest six (6) months after October 1, 2008, and one forty-eighth (1/48th) of the shares subject to the Option shall vest on the first day of each month thereafter.</footnote>
        <footnote id="F5">One fourth (1/4th) of the shares subject to the Option shall vest annually after January 1, 2009.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>Kevin D. Green by Lori L. Roll, attorney-in-fact</signatureName>
        <signatureDate>2009-03-31</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
<DOCUMENT>
<TYPE>EX-24
<SEQUENCE>2
<FILENAME>ex24green.txt
<TEXT>
POWER OF ATTORNEY

Know all by these presents, that the undersigned hereby constitutes and
appoints each of Howard G. Ervin, Lori Roll and Claes Glassell, signing
individually, the undersigned's true and lawful attorneys-in fact and
agents to:

1.  execute for and on behalf of the undersigned, an officer, director or
holder of 10% of more of a registered class of securities of Cerus
Corporation (the "Company"), Forms 3, 4 and 5 in accordance with Section
16(a) of the Securities Exchange Act of 1934, as amended (the "Exchange
Act") and the rules thereunder;

2. do and perform any and all acts for and on behalf of the undersigned
that may be necessary or desirable to complete and execute such Form 3, 4
or 5, complete and execute any amendment or amendments thereto, and timely
file such forms or amendments with the United States Securities and
Exchange Commission and any stock exchange or similar authority; and

3. take any other action of any nature whatsoever in connection with the
foregoing which, in the opinion of such attorney-in-fact, may be of
benefit, in the best interest of, or legally required by, the undersigned,
it being understood that the documents executed by such attorney-in-fact on
behalf of the undersigned pursuant to this Power of Attorney shall be in
such form and shall contain such terms and conditions as such attorney-in-
fact may approve in such attorney-in-fact's discretion.

The undersigned hereby grants to each such attorney-in-fact full power and
authority to do and perform any and every act and thing whatsoever
requisite, necessary, or proper to be done in the exercise of any of the
rights and powers herein granted, as fully to all intents and purposes as
the undersigned might or could do if personally present, with full power of
substitution or revocation, hereby ratifying and confirming all that such
attorney-in-fact, or such attorney-in-fact's substitute or substitutes,
shall lawfully do or cause to be done by virtue of this power of attorney
and the rights and powers herein granted.  The undersigned acknowledges
that the foregoing attorneys-in-fact, in serving in such capacity at the
request of the undersigned, are not assuming, nor is the Company assuming,
any of the undersigned's responsibilities to comply with Section 16 of the
Exchange Act.

This Power of Attorney shall remain in full force and effect until the
earliest to occur of (a) the undersigned no longer being required to file
Forms 3, 4 and 5 with respect to the undersigned's holdings of and
transactions in securities issued by the Company, (b) revocation by the
undersigned in a signed writing delivered to the foregoing attorneys-in-
fact or (c) as to any attorney-in-fact individually, until such attorney-
in-fact shall no longer be employed by the Company.

In Witness Whereof, the undersigned has caused this Power of Attorney to be
executed as of this 24th day of March, 2009.

/s/ Kevin Green
Kevin Dennis Green



775591 v1/SF
GMG701!.DOC
</TEXT>
</DOCUMENT>
</SUBMISSION>
