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    <periodOfReport>2019-01-25</periodOfReport>

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

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001166908</rptOwnerCik>
            <rptOwnerName>HADLEY PHILIP A</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O FACTSET RESEARCH SYSTEMS INC.</rptOwnerStreet1>
            <rptOwnerStreet2>601 MERRITT 7</rptOwnerStreet2>
            <rptOwnerCity>NORWALK</rptOwnerCity>
            <rptOwnerState>CT</rptOwnerState>
            <rptOwnerZipCode>06851</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
        </reportingOwnerRelationship>
    </reportingOwner>

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                <value>Common Stock</value>
            </securityTitle>
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                <value>2019-01-25</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>M</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>3016</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>94.84</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
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                    <value>612404</value>
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                <value>Common Stock</value>
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            <transactionDate>
                <value>2019-01-25</value>
            </transactionDate>
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                <transactionFormType>4</transactionFormType>
                <transactionCode>M</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
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            <transactionAmounts>
                <transactionShares>
                    <value>4564</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>92.22</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>616968</value>
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                <directOrIndirectOwnership>
                    <value>D</value>
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            </securityTitle>
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            <transactionDate>
                <value>2019-01-25</value>
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                    <value>3016</value>
                </transactionShares>
                <transactionPricePerShare>
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            <exerciseDate>
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            <expirationDate>
                <value>2019-01-31</value>
                <footnoteId id="F3"/>
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                </underlyingSecurityTitle>
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                </underlyingSecurityShares>
            </underlyingSecurity>
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            <ownershipNature>
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                    <value>D</value>
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            <securityTitle>
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                <value>2019-01-25</value>
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                <transactionShares>
                    <value>4564</value>
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                <transactionPricePerShare>
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            <expirationDate>
                <value>2019-01-31</value>
                <footnoteId id="F3"/>
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                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>0</value>
                </sharesOwnedFollowingTransaction>
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            <ownershipNature>
                <directOrIndirectOwnership>
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    <footnotes>
        <footnote id="F1">Options were granted on November 1, 2011 and vest over a 5 year period with 20% exercisable one year after the grant date and the remainder vesting at a rate of 1.67% per month thereafter.</footnote>
        <footnote id="F2">Options were granted on November 1, 2012 and vest over a 5 year period with 40% exercisable two years after the grant date and the remainder vesting at a rate of 1.67% per month thereafter.</footnote>
        <footnote id="F3">Mr. Hadley ceased to be an employee of FactSet Research Systems Inc. (the &quot;Company&quot;) on November 1, 2018, but will remain as the Chairman of the Board.  As Mr. Hadley is no longer an employee of the Company, his options expire 90 days from separation, consistent with the FactSet Research Systems Inc. Stock Option and Award Plan, as Amended and Restated.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ Philip A. Hadley</signatureName>
        <signatureDate>2019-01-28</signatureDate>
    </ownerSignature>
</ownershipDocument>
