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

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2012-09-17</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000320017</issuerCik>
        <issuerName>NeoStem, Inc.</issuerName>
        <issuerTradingSymbol>NBS</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001554792</rptOwnerCik>
            <rptOwnerName>RimAsia Capital Partners Manager, Ltd.</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>1807 HARBOUR CENTRE</rptOwnerStreet1>
            <rptOwnerStreet2>25 HARBOUR ROAD</rptOwnerStreet2>
            <rptOwnerCity>HONG KONG</rptOwnerCity>
            <rptOwnerState>F4</rptOwnerState>
            <rptOwnerZipCode></rptOwnerZipCode>
            <rptOwnerStateDescription>CHINA</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 Stock, par value $0.001 per share</value>
            </securityTitle>
            <transactionDate>
                <value>2012-09-17</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness></transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>30000</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0.7052</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>105306</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock, par value $0.001 per share</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>22409874</value>
                    <footnoteId id="F2"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See footnote</value>
                    <footnoteId id="F3"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">These 30,000 shares are being sold pursuant to a Rule 10b5-1 Sales Plan dated August 28, 2012, adopted by RimAsia Capital Partners Manager, Ltd. (&quot;RimAsia Manager&quot;), which is intended to comply with Rule 10b5-1.</footnote>
        <footnote id="F2">Reflects 22,409,874 shares of common stock owned by RimAsia Capital Partners, L.P. (&quot;RimAsia LP&quot;).</footnote>
        <footnote id="F3">Rim Asia Manager is the Fund Manager of RimAsia Capital Partners GP, L.P., a Cayman Islands exempted limited partnership (&quot;RimAsia GP&quot;) and the Manager of RimAsia LP. RimAsia GP is the general partner of RimAsia LP. RimAsia Capital Partners GP, Ltd. (&quot;RimAsia Ltd&quot;) is the general partner of RimAsia GP. Eric H.C. Wei, a member of the Company's board of directors, is the managing partner of RimAsia LP, an indirect partner of RimAsia GP, a director of RimAsia Ltd. and a director of RimAsia Manager. As a result, RimAsia Manager may be deemed to have sole power to vote certain of the securities held by RimAsia LP. RimAsia Manager disclaims beneficial ownership of such securities, except to the extent of its pecuniary interest therein.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ Catherine M. Vaczy, Esq., Attorney-in-Fact; RimAsia Capital Partners Manager, Ltd. By: Eric H.C. Wei</signatureName>
        <signatureDate>2012-09-18</signatureDate>
    </ownerSignature>
</ownershipDocument>
