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Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
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MIC-Info: RSA-MD5,RSA,
 IbujDX1tbV6VLNETNehARq6Wql9znAlc3rpf1yfGyiPbAH4zpb5vXjtT4nV2LTfZ
 nC523yN9igB0sKb869IaJA==

<SEC-DOCUMENT>0001233539-05-000001.txt : 20050224
<SEC-HEADER>0001233539-05-000001.hdr.sgml : 20050224
<ACCEPTANCE-DATETIME>20050224203956
ACCESSION NUMBER:		0001233539-05-000001
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20050222
FILED AS OF DATE:		20050224
DATE AS OF CHANGE:		20050224

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			PATTERSON LEONE D
		CENTRAL INDEX KEY:			0001233539

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-12798
		FILM NUMBER:		05638724

	BUSINESS ADDRESS:	
		STREET 1:		CHIRON CORP.
		STREET 2:		4560 HORTON STREET
		CITY:			EMERYVILLE
		STATE:			CA
		ZIP:			94608

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			CHIRON CORP
		CENTRAL INDEX KEY:			0000706539
		STANDARD INDUSTRIAL CLASSIFICATION:	PHARMACEUTICAL PREPARATIONS [2834]
		IRS NUMBER:				942754624
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		4560 HORTON ST
		CITY:			EMERYVILLE
		STATE:			CA
		ZIP:			94608
		BUSINESS PHONE:		5106558730
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>edgar.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0202</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2005-02-22</periodOfReport>

    <issuer>
        <issuerCik>0000706539</issuerCik>
        <issuerName>CHIRON CORP</issuerName>
        <issuerTradingSymbol>CHIR</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001233539</rptOwnerCik>
            <rptOwnerName>PATTERSON LEONE D</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>4560 HORTON STREET</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>EMERYVILLE</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>94608</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Vice President, Controller</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2005-02-22</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>1200</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>5743</value>
                    <footnoteId id="F2"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Employee Stock Option (Right to Buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>33.88</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2005-02-22</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F3"/>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>8000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <footnoteId id="F3"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <value>2006-02-22</value>
                <footnoteId id="F3"/>
            </exerciseDate>
            <expirationDate>
                <value>2015-02-22</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>8000</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>8000</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Represents restricted share rights covering 1,200 shares of the Issuer's common stock awarded to the Reporting Person in an exempt transaction under SEC Rule 16b-3(d), which share rights are subject to certain vesting.</footnote>
        <footnote id="F2">Includes the 1,200 shares subject to the restricted share rights awarded to the Reporting Person on February 22, 2005, plus additional restricted share rights covering 2,800 shares of the Issuer's common stock previously awarded to her and subject to a vesting schedule tied to her continued employment with the Issuer.</footnote>
        <footnote id="F3">Employee Stock Option granted under the Chiron 2004 Stock Compensation Plan in transaction exempt under Rule 16b-3.  Right to exercise vests as to 1/4 of the total shares on the first anniversary of the grant date and monthly thereafter as to 1/48 of the total shares, subject to acceleration of vesting upon certain qualifying terminations of employment.  The Chiron 2004 Stock Compensation  Plan has provisions permitting, in the discretion of the Administrator, the withholding of shares from the grant to satisfy income tax withholding.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>Leone D. Patterson by Naima Robinson as Atty-in-Fact</signatureName>
        <signatureDate>2005-02-24</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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