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

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2014-03-18</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001478242</issuerCik>
        <issuerName>Quintiles Transnational Holdings Inc.</issuerName>
        <issuerTradingSymbol>Q</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001107479</rptOwnerCik>
            <rptOwnerName>TPG Advisors III, Inc.</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O TPG GLOBAL, LLC</rptOwnerStreet1>
            <rptOwnerStreet2>301 COMMERCE STREET, SUITE 3300</rptOwnerStreet2>
            <rptOwnerCity>FORT WORTH</rptOwnerCity>
            <rptOwnerState>TX</rptOwnerState>
            <rptOwnerZipCode>76102</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001425876</rptOwnerCik>
            <rptOwnerName>TPG Advisors V, Inc.</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O TPG GLOBAL, LLC</rptOwnerStreet1>
            <rptOwnerStreet2>301 COMMERCE STREET, SUITE 3300</rptOwnerStreet2>
            <rptOwnerCity>FORT WORTH</rptOwnerCity>
            <rptOwnerState>TX</rptOwnerState>
            <rptOwnerZipCode>76102</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001339181</rptOwnerCik>
            <rptOwnerName>Tarrant Advisors, Inc</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O TPG GLOBAL, LLC</rptOwnerStreet1>
            <rptOwnerStreet2>301 COMMERCE STREET, SUITE 3300</rptOwnerStreet2>
            <rptOwnerCity>FORT WORTH</rptOwnerCity>
            <rptOwnerState>TX</rptOwnerState>
            <rptOwnerZipCode>76102</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0000860866</rptOwnerCik>
            <rptOwnerName>BONDERMAN DAVID</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O TPG GLOBAL, LLC</rptOwnerStreet1>
            <rptOwnerStreet2>301 COMMERCE STREET, SUITE 3300</rptOwnerStreet2>
            <rptOwnerCity>FORT WORTH</rptOwnerCity>
            <rptOwnerState>TX</rptOwnerState>
            <rptOwnerZipCode>76102</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001099776</rptOwnerCik>
            <rptOwnerName>COULTER JAMES G</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O TPG GLOBAL, LLC</rptOwnerStreet1>
            <rptOwnerStreet2>301 COMMERCE STREET, SUITE 3300</rptOwnerStreet2>
            <rptOwnerCity>FORT WORTH</rptOwnerCity>
            <rptOwnerState>TX</rptOwnerState>
            <rptOwnerZipCode>76102</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Shares</value>
            </securityTitle>
            <transactionDate>
                <value>2014-03-18</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness></transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>3564119</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>50.31</value>
                    <footnoteId id="F1"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>17858455</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See Explanation of Responses</value>
                    <footnoteId id="F2"/>
                    <footnoteId id="F3"/>
                    <footnoteId id="F4"/>
                    <footnoteId id="F5"/>
                    <footnoteId id="F6"/>
                    <footnoteId id="F7"/>
                    <footnoteId id="F8"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">The price represents the public offering price of $52.00 per share of Common Stock, par value $0.01 per share (each, a &quot;Share&quot;), of Quintiles Transnational Holdings Inc. (the &quot;Issuer&quot;), less the underwriting discount of $1.69 per Share.</footnote>
        <footnote id="F2">David Bonderman and James G. Coulter are officers and sole shareholders of each of (i) TPG Advisors III, Inc. (&quot;Advisors III&quot;), (ii) TPG Advisors V, Inc. (&quot;Advisors V&quot;) and (iii) Tarrant Advisors, Inc. (&quot;Tarrant Advisors&quot; and, together with Advisors III, Advisors V and Messrs. Bonderman and Coulter, the &quot;Reporting Persons&quot;).</footnote>
        <footnote id="F3">Advisors III is the general partner of TPG GenPar III, L.P., which is the general partner of TPG Quintiles Holdco, L.P. (&quot;Holdco I&quot;), which directly holds 3,554,517 Shares.</footnote>
        <footnote id="F4">Advisors V is the general partner of TPG Quintiles Holdco II, L.P. (&quot;Holdco II&quot;), which directly holds 13,605,959 Shares.</footnote>
        <footnote id="F5">Tarrant Advisors is the general partner of TPG Quintiles Holdco III, L.P. (&quot;Holdco III&quot; and, together with Holdco I and Holdco II, the &quot;TPG Funds&quot;), which directly holds 697,979 Shares.</footnote>
        <footnote id="F6">Because of the relationship between the Reporting Persons and the TPG Funds, the Reporting Persons may be deemed to beneficially own the securities reported herein to the extent of the greater of their respective direct or indirect pecuniary interests in the profits or capital accounts of the TPG Funds. Each Reporting Person and each TPG Fund disclaims beneficial ownership of the securities reported herein, except to the extent of such Reporting Person's or TPG Fund's pecuniary interest therein, if any.</footnote>
        <footnote id="F7">The TPG Funds have entered into a Shareholders Agreement, dated as of January 22, 2008 (as supplemented and amended, the &quot;Shareholders Agreement&quot;), with certain other holders (the &quot;Holders&quot;) of Shares. Because of the relationship between the TPG Funds and the Holders as a result of the Shareholders Agreement, the Reporting Persons may be deemed, pursuant to Rule 13d-3 under the Securities Exchange Act of 1934, as amended (the &quot;Exchange Act&quot;), to beneficially own the Shares held in the aggregate by the Holders. Each Reporting Person and each TPG Fund disclaims beneficial ownership of the Shares held by the Holders.</footnote>
        <footnote id="F8">Pursuant to Rule 16a-1(a)(4) under the Exchange Act, this filing shall not be deemed an admission that the Reporting Persons are, for purposes of Section 16 of the Exchange Act or otherwise, the beneficial owners of any equity securities in excess of their respective pecuniary interests.</footnote>
    </footnotes>

    <remarks>(9)  The Reporting Persons are jointly filing this Form 4 pursuant to Rule 16a-3(j) under the Exchange Act. (10)  Ronald Cami is signing on behalf of Messrs. Bonderman and Coulter pursuant to the authorization and designation letters dated July 1, 2013, which were previously filed with the Securities and Exchange Commission.</remarks>

    <ownerSignature>
        <signatureName>/s/ Ronald Cami, Vice President, TPG Advisors III, Inc. (9)</signatureName>
        <signatureDate>2014-03-19</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/ Ronald Cami, Vice President, TPG Advisors V, Inc. (9)</signatureName>
        <signatureDate>2014-03-19</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/ Ronald Cami, Vice President, Tarrant Advisors, Inc. (9)</signatureName>
        <signatureDate>2014-03-19</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/ Ronald Cami on behalf of David Bonderman (9)(10)</signatureName>
        <signatureDate>2014-03-19</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/ Ronald Cami on behalf of James G. Coulter (9)(10)</signatureName>
        <signatureDate>2014-03-19</signatureDate>
    </ownerSignature>
</ownershipDocument>
