<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2017-12-22</periodOfReport>

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

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001723733</rptOwnerCik>
            <rptOwnerName>Fernandez Gene D.</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>601 MERRITT 7</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>NORWALK</rptOwnerCity>
            <rptOwnerState>CT</rptOwnerState>
            <rptOwnerZipCode>06851</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isOfficer>1</isOfficer>
            <officerTitle>CTPO</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Non-Qualified Stock Option (right to buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>192.11</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2017-12-22</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>15363</value>
                </transactionShares>
                <transactionPricePerShare>
                    <footnoteId id="F2"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <value>2018-12-22</value>
                <footnoteId id="F1"/>
            </exerciseDate>
            <expirationDate>
                <value>2027-12-22</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>FactSet Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>15363</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>15363</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Mr. Fernandez was granted 15,363 stock options with an aggregate grant date fair value of $750,000 on December 22, 2017 pursuant to the FactSet Research Systems Inc. Employee Stock Option and Award Plan, as Amended and Restated. The option grant vests 20% annually on the anniversary date of the grant and are fully vested after five years.</footnote>
        <footnote id="F2">Column 8 has been intentionally left blank.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ Gene D. Fernandez</signatureName>
        <signatureDate>2017-12-27</signatureDate>
    </ownerSignature>
</ownershipDocument>
