-----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,
 Fi11Sov8EC8KSu1BJczBy57lRSbNf9jv2/8hNiYv3U4pDrjt0qbpHPo54fiw572W
 w7PcEJw/Y8YTxNEZtGbT3Q==

<SEC-DOCUMENT>0001179110-05-016899.txt : 20050823
<SEC-HEADER>0001179110-05-016899.hdr.sgml : 20050823
<ACCEPTANCE-DATETIME>20050823144050
ACCESSION NUMBER:		0001179110-05-016899
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20050819
FILED AS OF DATE:		20050823
DATE AS OF CHANGE:		20050823

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Valentine Keith
		CENTRAL INDEX KEY:			0001289408

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-50744
		FILM NUMBER:		051043452

	BUSINESS ADDRESS:	
		BUSINESS PHONE:		(858) 909-1800

	MAIL ADDRESS:	
		STREET 1:		4545 TOWNE CENTRE COURT
		CITY:			SAN DIEGO
		STATE:			CA
		ZIP:			92121

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			NUVASIVE INC
		CENTRAL INDEX KEY:			0001142596
		STANDARD INDUSTRIAL CLASSIFICATION:	SURGICAL & MEDICAL INSTRUMENTS & APPARATUS [3841]
		IRS NUMBER:				330768598
		STATE OF INCORPORATION:			DE

	BUSINESS ADDRESS:	
		STREET 1:		4545 TOWNE CENTRE COURT
		CITY:			SAN DIEGO
		STATE:			CA
		ZIP:			92121
		BUSINESS PHONE:		(858) 909-1800

	MAIL ADDRESS:	
		STREET 1:		4545 TOWNE CENTRE COURT
		CITY:			SAN DIEGO
		STATE:			CA
		ZIP:			92121
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>edgar.xml
<DESCRIPTION>FORM 4 -
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0202</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2005-08-19</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001142596</issuerCik>
        <issuerName>NUVASIVE INC</issuerName>
        <issuerTradingSymbol>NUVA</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001289408</rptOwnerCik>
            <rptOwnerName>Valentine Keith</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>4545 TOWNE CENTRE COURT</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>SAN DIEGO</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>92121</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>President</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2005-08-19</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F1"/>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>7500</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>18.7112</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>176205</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">The sale reported on this Form 4 was effected pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on September 14, 2004.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ Kevin C. O'Boyle, Attorney-in-fact</signatureName>
        <signatureDate>2005-08-22</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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