<?xml version="1.0" encoding="UTF-8"?><edgarSubmission xmlns="http://www.sec.gov/edgar/ownership" xmlns:ns2="http://www.sec.gov/edgar/common">
    <headerData>
        <submissionType>144</submissionType>
        <filerInfo>
            <filer>
                <filerCredentials>
                    <cik>0001646293</cik>
                    <ccc>XXXXXXXX</ccc>
                </filerCredentials>
            </filer>
            <liveTestFlag>LIVE</liveTestFlag>



        </filerInfo>
    </headerData>
    <formData>
        <issuerInfo>
            <issuerCik>0001262039</issuerCik>
            <issuerName>FORTINET INC</issuerName>
            <secFileNumber>001-34511</secFileNumber>
            <issuerAddress>
                <ns2:street1>909 Kifer Road</ns2:street1>
                <ns2:city>Sunnyvale</ns2:city>
                <ns2:stateOrCountry>CA</ns2:stateOrCountry>
                <ns2:zipCode>94086</ns2:zipCode>
            </issuerAddress>
            <issuerContactPhone>4082357700</issuerContactPhone>
            <nameOfPersonForWhoseAccountTheSecuritiesAreToBeSold>JUDITH KOON-LIEN SIM</nameOfPersonForWhoseAccountTheSecuritiesAreToBeSold>
            <relationshipsToIssuer>
                <relationshipToIssuer>Director</relationshipToIssuer>
            </relationshipsToIssuer>
        </issuerInfo>
        <securitiesInformation>
            <securitiesClassTitle>COMMON</securitiesClassTitle>
            <brokerOrMarketmakerDetails>
                <name>Morgan Stanley Smith Barney LLC Executive Financial Services</name>
                <address>
                    <ns2:street1>1 New York Plaza</ns2:street1>
                    <ns2:street2>8th Floor</ns2:street2>
                    <ns2:city>New York</ns2:city>
                    <ns2:stateOrCountry>NY</ns2:stateOrCountry>
                    <ns2:zipCode>10004</ns2:zipCode>
                </address>
            </brokerOrMarketmakerDetails>
            <noOfUnitsSold>20637</noOfUnitsSold>
            <aggregateMarketValue>1424778.48</aggregateMarketValue>
            <noOfUnitsOutstanding>763030948</noOfUnitsOutstanding>
            <approxSaleDate>03/06/2024</approxSaleDate>
            <securitiesExchangeName>NASDAQ</securitiesExchangeName>
        </securitiesInformation>
        <securitiesToBeSold>
            <securitiesClassTitle>Common</securitiesClassTitle>
            <acquiredDate>06/18/2020</acquiredDate>
            <natureOfAcquisitionTransaction>Restricted Stock Units</natureOfAcquisitionTransaction>
            <nameOfPersonfromWhomAcquired>Issuer</nameOfPersonfromWhomAcquired>
            <isGiftTransaction>N</isGiftTransaction>
            <amountOfSecuritiesAcquired>20637</amountOfSecuritiesAcquired>
            <paymentDate>06/18/2020</paymentDate>
            <natureOfPayment>N/A</natureOfPayment>
        </securitiesToBeSold>
        <nothingToReportFlagOnSecuritiesSoldInPast3Months>Y</nothingToReportFlagOnSecuritiesSoldInPast3Months>
        <remarks>The securities to be sold were acquired upon the vesting of restricted stock units during the period of 06/18/2020 through 09/30/2023.
</remarks>
        <noticeSignature>
            <noticeDate>03/06/2024</noticeDate>
            <planAdoptionDates>
                <planAdoptionDate>12/06/2023</planAdoptionDate>
            </planAdoptionDates>
            <signature>/s/ Judith Koon-Lien Sim</signature>
        </noticeSignature>
    </formData>
</edgarSubmission>
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144
0001646293
XXXXXXXX
LIVE
0001262039
FORTINET INC
001-34511
909 Kifer Road
Sunnyvale
CA
94086
4082357700
JUDITH KOON-LIEN SIM
Director
COMMON
Morgan Stanley Smith Barney LLC Executive Financial Services
1 New York Plaza
8th Floor
New York
NY
10004
20637
1424778.48
763030948
03/06/2024
NASDAQ
Common
06/18/2020
Restricted Stock Units
Issuer
N
20637
06/18/2020
N/A
Y
The securities to be sold were acquired upon the vesting of restricted stock units during the period of 06/18/2020 through 09/30/2023.
03/06/2024
12/06/2023
/s/ Judith Koon-Lien Sim