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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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<SEC-DOCUMENT>0001339604-06-000003.txt : 20060322
<SEC-HEADER>0001339604-06-000003.hdr.sgml : 20060322
<ACCEPTANCE-DATETIME>20060322213215
ACCESSION NUMBER:		0001339604-06-000003
CONFORMED SUBMISSION TYPE:	4/A
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20060104
FILED AS OF DATE:		20060322
DATE AS OF CHANGE:		20060322

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Blair Nancy E
		CENTRAL INDEX KEY:			0001339604

	FILING VALUES:
		FORM TYPE:		4/A
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-11869
		FILM NUMBER:		06704869

	BUSINESS ADDRESS:	
		BUSINESS PHONE:		2032372333

	MAIL ADDRESS:	
		STREET 1:		BLAIR & POTTS  TWO STAMFORD PLAZA
		STREET 2:		281 TRESSER BLVD
		CITY:			STAMFORD
		STATE:			CT
		ZIP:			06901

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			FACTSET RESEARCH SYSTEMS INC
		CENTRAL INDEX KEY:			0001013237
		STANDARD INDUSTRIAL CLASSIFICATION:	SERVICES-COMPUTER PROGRAMMING, DATA PROCESSING, ETC. [7370]
		IRS NUMBER:				133362547
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			0831

	BUSINESS ADDRESS:	
		STREET 1:		601 MERRITT 7
		CITY:			NORWALK
		STATE:			CT
		ZIP:			06851
		BUSINESS PHONE:		2038101000

	MAIL ADDRESS:	
		STREET 1:		601 MERRITT 7
		CITY:			NORWALK
		STATE:			CT
		ZIP:			06851
</SEC-HEADER>
<DOCUMENT>
<TYPE>4/A
<SEQUENCE>1
<FILENAME>primary_doc.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0202</schemaVersion>

    <documentType>4/A</documentType>

    <periodOfReport>2006-01-04</periodOfReport>

    <dateOfOriginalSubmission>2006-01-19</dateOfOriginalSubmission>

    <notSubjectToSection16>1</notSubjectToSection16>

    <issuer>
        <issuerCik>0001013237</issuerCik>
        <issuerName>FACTSET RESEARCH SYSTEMS INC</issuerName>
        <issuerTradingSymbol>FDS</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001339604</rptOwnerCik>
            <rptOwnerName>Blair Nancy E</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>BLAIR &amp; POTTS  TWO STAMFORD PLAZA</rptOwnerStreet1>
            <rptOwnerStreet2>281 TRESSER BLVD</rptOwnerStreet2>
            <rptOwnerCity>STAMFORD</rptOwnerCity>
            <rptOwnerState>CT</rptOwnerState>
            <rptOwnerZipCode>06901</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Factset Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2006-01-04</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>5</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value>E</value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>3600555</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>40.305</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>389</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>Executors of Estate</value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable>
        <derivativeHolding>
            <securityTitle>
                <value>Common Stock Options</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>0</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <value>2005-12-22</value>
            </exerciseDate>
            <expirationDate>
                <value>2006-09-06</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>22500</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>22500</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>Executors of Estate</value>
                </natureOfOwnership>
            </ownershipNature>
        </derivativeHolding>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Including 1,500,000 shares of Factset common stock held by Wille Family Investors LLC.  The estate is the non-managing member of Wille Family Investors LLC and Brian C. Wille is the manager of Wille Family Investors LLC.</footnote>
    </footnotes>

    <remarks>(*) This Form 4 is also filed on behalf of the Estate of Howard E. Wille, P.O. Box 1214, Stamford, CT 06904-1214 and the co-executor of the estate, Brian C. Wille, 1088 Park Avenue, New York, NY 10128.</remarks>

    <ownerSignature>
        <signatureName>/s/ Nancy E. Blair</signatureName>
        <signatureDate>2006-03-22</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/ Nancy E. Blair for the Estate</signatureName>
        <signatureDate>2006-03-22</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/ Brian C. Wille</signatureName>
        <signatureDate>2006-03-22</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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