<SEC-DOCUMENT>0001127602-23-025174.txt : 20231003
<SEC-HEADER>0001127602-23-025174.hdr.sgml : 20231003
<ACCEPTANCE-DATETIME>20231003161635
ACCESSION NUMBER:		0001127602-23-025174
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20231002
FILED AS OF DATE:		20231003
DATE AS OF CHANGE:		20231003

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			SMITH SANDFORD D
		CENTRAL INDEX KEY:			0001243004

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-50633
		FILM NUMBER:		231303849

	MAIL ADDRESS:	
		STREET 1:		C/O ARIAD PHARMACEUTICALS INC
		STREET 2:		26 LANDSDOWNE STREET
		CITY:			CAMBRIDGE
		STATE:			MA
		ZIP:			02139

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			CYTOKINETICS INC
		CENTRAL INDEX KEY:			0001061983
		STANDARD INDUSTRIAL CLASSIFICATION:	PHARMACEUTICAL PREPARATIONS [2834]
		IRS NUMBER:				943291317
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		350 OYSTER POINT BOULEVARD
		STREET 2:		.
		CITY:			SOUTH SAN FRANCISCO
		STATE:			CA
		ZIP:			94080
		BUSINESS PHONE:		(650) 624-3000

	MAIL ADDRESS:	
		STREET 1:		350 OYSTER POINT BOULEVARD
		CITY:			SOUTH SAN FRANCISCO
		STATE:			CA
		ZIP:			94080
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>form4.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0508</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2023-10-02</periodOfReport>

    <issuer>
        <issuerCik>0001061983</issuerCik>
        <issuerName>CYTOKINETICS INC</issuerName>
        <issuerTradingSymbol>CYTK</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001243004</rptOwnerCik>
            <rptOwnerName>SMITH SANDFORD D</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>350 OYSTER POINT BLVD</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>SOUTH SAN FRANCISCO</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>94080</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
        </reportingOwnerRelationship>
    </reportingOwner>

    <aff10b5One>0</aff10b5One>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2023-10-02</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F1"/>
            </transactionCoding>
            <transactionTimeliness></transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>448</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>27.88</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>18653</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">Shares issued at Reporting Person's election pursuant to Issuer's stock in lieu of cash for all or part of directors' annual base retainer program.  Shares are full vested from the moment of grant.  Shares issued at per share price of $27.88, representing the Issuer's closing stock price on October 2, 2023.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ John Faurescu, attorney-in-fact for Mr. Smith</signatureName>
        <signatureDate>2023-10-03</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
