<SUBMISSION>
<ACCESSION-NUMBER>0001181431-07-062107
<TYPE>3
<PUBLIC-DOCUMENT-COUNT>1
<PERIOD>20071011
<FILING-DATE>20071012
<DATE-OF-FILING-DATE-CHANGE>20071012
<ISSUER>
<COMPANY-DATA>
<CONFORMED-NAME>OSI SYSTEMS INC
<CIK>0001039065
<ASSIGNED-SIC>3674
<IRS-NUMBER>330238801
<STATE-OF-INCORPORATION>CA
<FISCAL-YEAR-END>0630
</COMPANY-DATA>
<BUSINESS-ADDRESS>
<STREET1>12525 CHADRON AVE
<CITY>HAWTHORNE
<STATE>CA
<ZIP>90250
<PHONE>3109780516
</BUSINESS-ADDRESS>
<MAIL-ADDRESS>
<STREET1>12525 CHADRON AVENUE
<CITY>HAWTHORNE
<STATE>CA
<ZIP>90250
</MAIL-ADDRESS>
</ISSUER>
<REPORTING-OWNER>
<OWNER-DATA>
<CONFORMED-NAME>ALIABADI MANOOCHER M
<CIK>0001047062
</OWNER-DATA>
<FILING-VALUES>
<FORM-TYPE>3
<ACT>34
<FILE-NUMBER>000-23125
<FILM-NUMBER>071170605
</FILING-VALUES>
<BUSINESS-ADDRESS>
<STREET1>C/O OSI SYSTEMS INC
<STREET2>12525 CHADRON AVE
<CITY>HAWTHORNE
<STATE>CA
<ZIP>70250
</BUSINESS-ADDRESS>
<MAIL-ADDRESS>
<STREET2>12525 CHADRON AVE
<CITY>HAWTHORNE
<STATE>CA
<ZIP>90250
</MAIL-ADDRESS>
<FORMER-NAME>
<FORMER-CONFORMED-NAME>ALIABADI MANOOCHER
<DATE-CHANGED>19970930
</FORMER-NAME>
</REPORTING-OWNER>
<DOCUMENT>
<TYPE>3
<SEQUENCE>1
<FILENAME>rrd174973.xml
<DESCRIPTION>FORM 3
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0202</schemaVersion>

    <documentType>3</documentType>

    <periodOfReport>2007-10-11</periodOfReport>

    <noSecuritiesOwned>0</noSecuritiesOwned>

    <issuer>
        <issuerCik>0001039065</issuerCik>
        <issuerName>OSI SYSTEMS INC</issuerName>
        <issuerTradingSymbol>OSIS</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001047062</rptOwnerCik>
            <rptOwnerName>ALIABADI MANOOCHER M</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>12525 CHADRON AVE</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>HAWTHORNE</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>90250</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>President/GM OSI Optoelectroni</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>29012</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See Footnote 1</value>
                    <footnoteId id="F1"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <derivativeTable>
        <derivativeHolding>
            <securityTitle>
                <value>Option to Purchase Common Stock</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>16.31</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <value>2007-01-08</value>
            </exerciseDate>
            <expirationDate>
                <value>2008-01-07</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>2250</value>
                    <footnoteId id="F2"/>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>Option to Purchase Common Stock</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>16.10</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <value>2007-08-14</value>
            </exerciseDate>
            <expirationDate>
                <value>2008-08-13</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>1500</value>
                    <footnoteId id="F2"/>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>Option to Purchase Common Stock</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>19.88</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <value>2007-03-02</value>
            </exerciseDate>
            <expirationDate>
                <value>2009-03-01</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>1500</value>
                    <footnoteId id="F2"/>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>Option to Purchase Common Stock</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>17.19</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <value>2008-03-10</value>
            </exerciseDate>
            <expirationDate>
                <value>2010-03-09</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>2500</value>
                    <footnoteId id="F3"/>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>Option to Purchase Common Stock</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>19.58</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <value>2009-01-11</value>
            </exerciseDate>
            <expirationDate>
                <value>2011-01-10</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>2500</value>
                    <footnoteId id="F4"/>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Shares are held with spouse.</footnote>
        <footnote id="F2">Options are fully vested.</footnote>
        <footnote id="F3">Options are 50% vested.</footnote>
        <footnote id="F4">Options are 25% vested.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ Manoocher Mansouri Aliabadi</signatureName>
        <signatureDate>2007-10-11</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SUBMISSION>
