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Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
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MIC-Info: RSA-MD5,RSA,
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 okbth+wQ4GNBRjjyQaxTKg==

<SEC-DOCUMENT>0001229438-05-000001.txt : 20050503
<SEC-HEADER>0001229438-05-000001.hdr.sgml : 20050503
<ACCEPTANCE-DATETIME>20050503160242
ACCESSION NUMBER:		0001229438-05-000001
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20050429
FILED AS OF DATE:		20050503
DATE AS OF CHANGE:		20050503

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

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			FREDERICKS J RICHARD
		CENTRAL INDEX KEY:			0001229438

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-12798
		FILM NUMBER:		05795117

	BUSINESS ADDRESS:	
		STREET 1:		C/O CHIRON CORP
		STREET 2:		4560 HORTON STREET
		CITY:			EMERYVILLE
		STATE:			CA
		ZIP:			94608-2916
		BUSINESS PHONE:		5109232910
</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>2005-04-29</periodOfReport>

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

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001229438</rptOwnerCik>
            <rptOwnerName>FREDERICKS J RICHARD</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>4560 HORTON STREET</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>EMERYVILLE</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>94608</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2005-04-29</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>4775</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>9379</value>
                    <footnoteId id="F2"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">Represents share rights award for 4,775 shares of the Issuer's common stock made to the Reporting Person in a transaction exempt under SEC Rule 16b-3(d).  The shares underlying the award are fully vested but will become issuable upon the Reporting Person's cessation of service as a member of the Issuer's board of directors.</footnote>
        <footnote id="F2">Includes (i) the 4,775 shares subject to the share rights award reported above on Table I, and (ii) a share rights award for an additional 4,604 vested shares which will become issuable upon the Reporting Person's cessation of service as a member of the Issuer's board of directors</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>J. Richard Fredericks by Naima Robinson as Atty-in-Fact</signatureName>
        <signatureDate>2005-05-03</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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