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

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2018-07-31</periodOfReport>

    <notSubjectToSection16>1</notSubjectToSection16>

    <issuer>
        <issuerCik>0000881890</issuerCik>
        <issuerName>ABAXIS INC</issuerName>
        <issuerTradingSymbol>ABAX</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001190435</rptOwnerCik>
            <rptOwnerName>CASEY MICHAEL D</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O ABAXIS, INC.</rptOwnerStreet1>
            <rptOwnerStreet2>3240 WHIPPLE ROAD</rptOwnerStreet2>
            <rptOwnerCity>UNION CITY</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>94587</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2018-07-31</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>D</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F1"/>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>29200</value>
                </transactionShares>
                <transactionPricePerShare>
                    <footnoteId id="F1"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>0</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Restricted Stock Units</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>0</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2018-07-31</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>D</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>5500</value>
                </transactionShares>
                <transactionPricePerShare>
                    <footnoteId id="F2"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F2"/>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F3"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>0</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>0</value>
                    <footnoteId id="F2"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Pursuant to the Agreement and Plan of Merger (the &quot;Merger Agreement&quot;) dated May 15, 2018, by and among Abaxis, Inc., a California corporation (the &quot;Issuer&quot;), Zoetis Inc., a Delaware corporation (&quot;Parent&quot;), and Zeus Merger Sub, Inc., a California corporation and an indirect wholly owned subsidiary of Parent (&quot;Merger Sub&quot;), on July 31, 2018, Merger Sub merged with and into the Issuer (the &quot;Merger&quot;), with the Issuer continuing as the surviving corporation and an indirect wholly owned subsidiary of Parent. In connection with the Merger, these shares were cancelled and converted into the right to receive $83.00 in cash, without interest, per share, subject to the terms and conditions of the Merger Agreement (the &quot;Merger Consideration&quot;).</footnote>
        <footnote id="F2">Pursuant to the terms of the Merger Agreement, at the effective time of the Merger (the &quot;Effective Time&quot;), each of these unvested restricted stock units vested automatically in accordance with their existing terms and were cancelled and automatically converted into the right to receive the Merger Consideration in respect of each share of Issuer common stock underlying such awards. Each of these vested restricted stock units converted into the right to receive the Merger Consideration in respect of each share of Issuer common stock underlying such awards.</footnote>
        <footnote id="F3">Not applicable.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ Michael D. Casey</signatureName>
        <signatureDate>2018-08-02</signatureDate>
    </ownerSignature>
</ownershipDocument>
