<SUBMISSION>
<ACCESSION-NUMBER>0001209191-07-061730
<TYPE>3
<PUBLIC-DOCUMENT-COUNT>2
<PERIOD>20071025
<FILING-DATE>20071105
<DATE-OF-FILING-DATE-CHANGE>20071105
<ISSUER>
<COMPANY-DATA>
<CONFORMED-NAME>F5 NETWORKS INC
<CIK>0001048695
<ASSIGNED-SIC>3576
<IRS-NUMBER>911714307
<STATE-OF-INCORPORATION>WA
<FISCAL-YEAR-END>0930
</COMPANY-DATA>
<BUSINESS-ADDRESS>
<STREET1>401 ELLIOT AVE WEST
<STREET2>STE 500
<CITY>SEATTLE
<STATE>WA
<ZIP>98119
<PHONE>2062725555
</BUSINESS-ADDRESS>
<MAIL-ADDRESS>
<STREET1>401 ELLIOT AVE WEST
<STREET2>STE 500
<CITY>SEATTLE
<STATE>WA
<ZIP>98119
</MAIL-ADDRESS>
<FORMER-COMPANY>
<FORMER-CONFORMED-NAME>F5 LABS INC
<DATE-CHANGED>19990305
</FORMER-COMPANY>
</ISSUER>
<REPORTING-OWNER>
<OWNER-DATA>
<CONFORMED-NAME>Anderson Mark
<CIK>0001417100
</OWNER-DATA>
<FILING-VALUES>
<FORM-TYPE>3
<ACT>34
<FILE-NUMBER>000-26041
<FILM-NUMBER>071213322
</FILING-VALUES>
<BUSINESS-ADDRESS>
<PHONE>206-272-5555
</BUSINESS-ADDRESS>
<MAIL-ADDRESS>
<STREET1>C/O F5 NETWORKS, INC.
<STREET2>401 ELLIOTT AVE. WEST
<CITY>SEATTLE
<STATE>WA
<ZIP>98119
</MAIL-ADDRESS>
</REPORTING-OWNER>
<DOCUMENT>
<TYPE>3
<SEQUENCE>1
<FILENAME>doc3.xml
<DESCRIPTION>FORM 3 SUBMISSION
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0202</schemaVersion>

    <documentType>3</documentType>

    <periodOfReport>2007-10-25</periodOfReport>

    <noSecuritiesOwned>0</noSecuritiesOwned>

    <issuer>
        <issuerCik>0001048695</issuerCik>
        <issuerName>F5 NETWORKS INC</issuerName>
        <issuerTradingSymbol>FFIV</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001417100</rptOwnerCik>
            <rptOwnerName>Anderson Mark</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>401 ELLIOTT AVENUE WEST</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>SEATTLE</rptOwnerCity>
            <rptOwnerState>WA</rptOwnerState>
            <rptOwnerZipCode>98119</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Sr. VP, Worldwide Sales</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>2730</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <derivativeTable>
        <derivativeHolding>
            <securityTitle>
                <value>Restricted Stock Units</value>
                <footnoteId id="F1"/>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>0.00</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <value>2006-10-01</value>
                <footnoteId id="F2"/>
            </exerciseDate>
            <expirationDate>
                <value>2015-09-30</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>3750</value>
                    <footnoteId id="F3"/>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>Restricted Stock Units</value>
                <footnoteId id="F1"/>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>0.00</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <value>2006-10-01</value>
                <footnoteId id="F4"/>
            </exerciseDate>
            <expirationDate>
                <value>2016-07-01</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>7500</value>
                    <footnoteId id="F3"/>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>Stock Award</value>
                <footnoteId id="F1"/>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>0.00</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <value>2007-11-01</value>
                <footnoteId id="F5"/>
            </exerciseDate>
            <expirationDate>
                <value>2017-08-01</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>10000</value>
                    <footnoteId id="F6"/>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>Non-Qualified Stock Option (right to buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>16.475</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <value>2005-10-25</value>
                <footnoteId id="F7"/>
            </exerciseDate>
            <expirationDate>
                <value>2014-10-25</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>43751</value>
                    <footnoteId id="F8"/>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Right to receive shares of F5 Networks, Inc. common stock on the vest date.</footnote>
        <footnote id="F2">5,000 (Pre-Stock Split) RSUs were granted on 9/30/2005. The RSUs vested 1/8 on October 1, 2006, with the remainder vesting 1/8 on the first day of the subsequent seven quarters. 1/1/2008 is the first vest date for the outstanding RSUs.</footnote>
        <footnote id="F3">Indicates the number of RSUs outstanding as of October 25, 2007.</footnote>
        <footnote id="F4">10,000 (Pre-Stock Split) RSUs were granted on 7/1/2006. The RSUs vest quarterly over a 2 year period from the date of grant. 1/1/2008 is the first vest date for the outstanding RSUs.</footnote>
        <footnote id="F5">10,000 Stock Award shares were granted on 8/1/2007. The Stock Award shares vest quarterly over a 2 year period from the date of grant.</footnote>
        <footnote id="F6">Indicates the number of Stock Award shares outstanding as of 10/25/2007.</footnote>
        <footnote id="F7">75,000 (Pre-Stock Split) Non-Qualified Stock Options were granted on 10/25/2004. Options vest 25% one year following the date of grant and the remaining 75% vest monthly over the following three year period.</footnote>
        <footnote id="F8">Indicates the number of options outstanding as of October 25, 2007.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ Jeffrey A. Christianson by Power of Attorney</signatureName>
        <signatureDate>2007-11-05</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
<DOCUMENT>
<TYPE>EX-24.3_209713
<SEQUENCE>2
<FILENAME>poa.txt
<DESCRIPTION>POA DOCUMENT
<TEXT>
POWER OF ATTORNEY

          The undersigned hereby constitutes and appoints Jeffrey A.
Christianson, Scot Rogers or John E. Rodriguez, or either of them, as the
undersigned's true and lawful attorney-in-fact to:
(1)        execute for and on behalf of the undersigned, in the undersigned's
capacity as an officer and/or director of F5 Networks, Inc. (the "Company"),
Forms 3, 4, and 5 in accordance with Section 16(a) of the Securities Exchange
Act of 1934 and the rules thereunder;
(2)        do and perform any and all acts for and on behalf of the undersigned
which may be necessary or desirable to complete and execute any such Form 3, 4,
or 5, complete and execute any amendment or amendments thereto, and timely file
such form with the United States Securities and Exchange Commission and any
stock exchange or similar authority; and
(3)        take any other action of any type whatsoever in connection with the
foregoing which, in the opinion of such attorney-in-fact, may be of benefit to,
in the best interest of, or legally required by, the undersigned, it being
understood that the documents executed by such attorney-in-fact on behalf of the
undersigned pursuant to this Power of Attorney shall be in such form and shall
contain such terms and conditions as such attorney-in-fact may approve in such
attorney-in-fact's discretion.
	The undersigned hereby grants to each such attorney-in-fact full power and
authority to do and perform any and every act and thing whatsoever requisite,
necessary, or proper to be done in the exercise of any of the rights and powers
herein granted, as fully to all intents and purposes as the undersigned might or
could do if personally present, with full power of substitution or revocation,
hereby ratifying and confirming all that such attorney-in-fact, or such
attorney-in-fact's substitute or substitutes, shall lawfully do or cause to be
done by virtue of this power of attorney and the rights and powers herein
granted.  The undersigned acknowledges that the foregoing attorneys-in-fact, in
serving in such capacity at the request of the undersigned, are not assuming,
nor is the Company assuming, any of the undersigned's responsibilities to comply
with Section 16 of the Securities Exchange Act of 1934.

         This Power of Attorney shall remain in full force and effect until the
undersigned is no longer required to file Forms 3, 4, and 5 with respect to the
undersigned's holdings of and transactions in securities issued by the Company,
unless earlier revoked by the undersigned in a signed writing delivered to the
foregoing attorneys-in-fact.

IN WITNESS WHEREOF, the undersigned has caused this Power of Attorney to be
executed as of this 31st day of October, 2007.


/s/ Mark Anderson
Mark Anderson

</TEXT>
</DOCUMENT>
</SUBMISSION>
