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Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
Originator-Key-Asymmetric:
 MFgwCgYEVQgBAQICAf8DSgAwRwJAW2sNKK9AVtBzYZmr6aGjlWyK3XmZv3dTINen
 TWSM7vrzLADbmYQaionwg5sDW3P6oaM5D3tdezXMm7z1T+B+twIDAQAB
MIC-Info: RSA-MD5,RSA,
 FH55sG3TlYjxuYdH3rFLd4b+PHippByFUbDlib2W6yq6o9fbKWgJ9Ax02iC2xDnW
 JspGduFHPm5tw8rM6msEyw==

<SEC-DOCUMENT>0001179110-06-017809.txt : 20060901
<SEC-HEADER>0001179110-06-017809.hdr.sgml : 20060901
<ACCEPTANCE-DATETIME>20060901135059
ACCESSION NUMBER:		0001179110-06-017809
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20060901
FILED AS OF DATE:		20060901
DATE AS OF CHANGE:		20060901

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			PHARSIGHT CORP
		CENTRAL INDEX KEY:			0001040853
		STANDARD INDUSTRIAL CLASSIFICATION:	SERVICES-PREPACKAGED SOFTWARE [7372]
		IRS NUMBER:				770401273
		STATE OF INCORPORATION:			CA
		FISCAL YEAR END:			0331

	BUSINESS ADDRESS:	
		STREET 1:		321 E. EVELYN AVENUE
		STREET 2:		3RD FLOOR
		CITY:			MOUNTAIN VIEW
		STATE:			CA
		ZIP:			94041
		BUSINESS PHONE:		6503143800

	MAIL ADDRESS:	
		STREET 1:		321 E. EVELYN AVENUE
		STREET 2:		3RD FLOOR
		CITY:			MOUNTAIN VIEW
		STATE:			CA
		ZIP:			94041

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Alloy Ventures 2000, LLC
		CENTRAL INDEX KEY:			0001317231

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-31253
		FILM NUMBER:		061071080

	BUSINESS ADDRESS:	
		STREET 1:		400 HAMILTON AVENUE
		STREET 2:		4TH FLOOR
		CITY:			PALO ALTO
		STATE:			CA
		ZIP:			94301
		BUSINESS PHONE:		650-687-5000

	MAIL ADDRESS:	
		STREET 1:		400 HAMILTON AVENUE
		STREET 2:		4TH FLOOR
		CITY:			PALO ALTO
		STATE:			CA
		ZIP:			94301
</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>2006-09-01</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001040853</issuerCik>
        <issuerName>PHARSIGHT CORP</issuerName>
        <issuerTradingSymbol>PHST</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001317231</rptOwnerCik>
            <rptOwnerName>Alloy Ventures 2000, LLC</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>400 HAMILTON AVE., 4TH FLOOR</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>PALO ALTO</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>94301</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable></nonDerivativeTable>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Series B Redeemable Convertible Preferred Stock</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <footnoteId id="F1"/>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2006-09-01</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>18142</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                    <footnoteId id="F2"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <value>2006-09-01</value>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F1"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>72568</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>126994</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Each share of Series B redeemable convertible preferred stock is convertible into four shares of Pharsight's common stock at the election of the holder or upon the occurrence of certain other events described in issuer's certificate of designation of Series  A and Series B convertible preferred stock.</footnote>
        <footnote id="F2">Issued as a dividend to Series A redeemable convertible preferred stockholders.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/Tony DiBona, Managing Member</signatureName>
        <signatureDate>2006-09-01</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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