<SUBMISSION>
<ACCESSION-NUMBER>0000950124-05-002434
<TYPE>S-8
<PUBLIC-DOCUMENT-COUNT>3
<FILING-DATE>20050415
<DATE-OF-FILING-DATE-CHANGE>20050415
<EFFECTIVENESS-DATE>20050415
<FILER>
<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>
<FILING-VALUES>
<FORM-TYPE>S-8
<ACT>33
<FILE-NUMBER>333-124092
<FILM-NUMBER>05753198
</FILING-VALUES>
<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>
</FILER>
<DOCUMENT>
<TYPE>S-8
<SEQUENCE>1
<FILENAME>v07907orsv8.htm
<DESCRIPTION>FORM S-8
<TEXT>
<HTML>
<HEAD>
<TITLE>sv8</TITLE>
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<BODY bgcolor="#FFFFFF">
<!-- PAGEBREAK -->
<H5 align="left" style="page-break-before:always"><A HREF="#toc">Table of Contents</A></H5><P>
<DIV style="font-family: 'Times New Roman',Times,serif">

<DIV align="center">
<TABLE style="font-size: 10pt" cellspacing="0" border="0" cellpadding="0" width="100%">
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<TR valign="bottom">
    <TD align="left" valign="top"><B>As filed with the Securities and Exchange Commission on April&nbsp;15, 2005</B>
</TD>
    <TD>&nbsp;</TD>
    <TD align="right" valign="top"><B>Registration No.&nbsp;333-</B>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</TD>
</TR>
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</TABLE>
</DIV>

<DIV style="width: 100%; border-bottom: 2pt solid black; font-size: 1pt">&nbsp;</DIV>
<DIV style="width: 100%; border-bottom: 1pt solid black; font-size: 1pt">&nbsp;</DIV>

<P align="center" style="font-size: 14pt"><B>SECURITIES AND EXCHANGE COMMISSION</B>

<DIV align="center" style="font-size: 12pt"><B>Washington, D.C. 20549</B>
</DIV>

<P align="center" style="font-size: 18pt"><B>FORM S-8</B>

<P align="center" style="font-size: 12pt"><B>REGISTRATION STATEMENT<BR>
UNDER<BR>
THE SECURITIES ACT OF 1933</B>

<P align="center" style="font-size: 24pt"><B><U>F5 NETWORKS, INC.</U></B>

<DIV align="center" style="font-size: 10pt"><B>(Exact Name of Registrant as Specified in Its Charter)</B></DIV>

<P align="center" style="font-size: 10pt"><U><B>Washington</B></U><BR>
<B>(State or Other Jurisdiction<BR>
of Incorporation or Organization)</B>

<P align="center" style="font-size: 10pt"><U><B>91-1714307</B></U><BR>
<B>(I.R.S. Employer Identification No.)</B>

<P align="center" style="font-size: 10pt"><U><B>401 Elliott Avenue West, Seattle, Washington 98119</B></U><BR>
<B>(Address of Principal Executive Offices)</B>

<P align="center" style="font-size: 10pt"><U><B>2005 Equity Incentive Plan</B></U><BR>
<B>(Full Title of the Plan)</B>

<P align="center" style="font-size: 10pt"><B>Joann Reiter<BR>
F5 Networks, Inc.<BR>
401 Elliott Avenue West</B><BR>
<U><B>Seattle, WA 98119</B></U><BR>
<B>(Name and Address of Agent for Service)</B>

<P align="center" style="font-size: 10pt"><U><B>(206)&nbsp;272-5555</B></U><BR>
<B>(Telephone Number, Including Area Code, of Agent for Service)</B>

<P align="center" style="font-size: 10pt"><B>CALCULATION OF REGISTRATION FEE</B>

<DIV align="center">
<TABLE style="font-size: 10pt" cellspacing="0" border="0" cellpadding="0" width="100%">
<!-- Begin Table Head -->
<TR valign="bottom">
    <TD width="1%">&nbsp;</TD>
    <TD width="58%">&nbsp;</TD>
    <TD width="1%">&nbsp;</TD><!-- VRule -->
    <TD width="1%">&nbsp;</TD>
    <TD width="5%">&nbsp;</TD>
    <TD width="5%">&nbsp;</TD>
    <TD width="1%">&nbsp;</TD>
    <TD width="1%">&nbsp;</TD><!-- VRule -->
    <TD width="1%">&nbsp;</TD>
    <TD width="1%">&nbsp;</TD>
    <TD width="5%">&nbsp;</TD>
    <TD width="1%">&nbsp;</TD>
    <TD width="1%">&nbsp;</TD><!-- VRule -->
    <TD width="1%">&nbsp;</TD>
    <TD width="1%">&nbsp;</TD>
    <TD width="5%">&nbsp;</TD>
    <TD width="1%">&nbsp;</TD>
    <TD width="1%">&nbsp;</TD><!-- VRule -->
    <TD width="1%">&nbsp;</TD>
    <TD width="1%">&nbsp;</TD>
    <TD width="5%">&nbsp;</TD>
    <TD width="1%">&nbsp;</TD>
    <TD width="1%">&nbsp;</TD>
</TR>

<TR style="font-size: 1px" valign="bottom">
    <TD nowrap align="left" colspan="21" style="border-bottom: 3px solid #000000">&nbsp;</TD>
</TR>

<TR style="font-size: 8pt" valign="bottom">    <TD width="1%">&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD style="border-right: 2px solid #000000">&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD style="border-right: 2px solid #000000">&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD nowrap align="center" colspan="2"><B>Proposed</B></TD>
    <TD>&nbsp;</TD>
    <TD style="border-right: 2px solid #000000">&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD nowrap align="center" colspan="2"><B>Proposed</B></TD>
    <TD>&nbsp;</TD>
    <TD style="border-right: 2px solid #000000">&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD nowrap align="center" colspan="2">&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD width="1%">&nbsp;</TD>
</TR>
<TR style="font-size: 8pt" valign="bottom">    <TD width="1%">&nbsp;</TD>
    <TD nowrap align="center"><B>Title of</B></TD>
    <TD style="border-right: 2px solid #000000">&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD style="border-right: 2px solid #000000">&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD nowrap align="center" colspan="2"><B>Maximum</B></TD>
    <TD>&nbsp;</TD>
    <TD style="border-right: 2px solid #000000">&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD nowrap align="center" colspan="2"><B>Maximum</B></TD>
    <TD>&nbsp;</TD>
    <TD style="border-right: 2px solid #000000">&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD nowrap align="center" colspan="2"><B>Amount of</B></TD>
    <TD>&nbsp;</TD>
    <TD width="1%">&nbsp;</TD>
</TR>
<TR style="font-size: 8pt" valign="bottom">    <TD width="1%">&nbsp;</TD>
    <TD nowrap align="center"><B>Securities</B></TD>
    <TD style="border-right: 2px solid #000000">&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD nowrap align="center" colspan="2"><B>Amount To Be</B></TD>
    <TD>&nbsp;</TD>
    <TD style="border-right: 2px solid #000000">&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD nowrap align="center" colspan="2"><B>Offering Price</B></TD>
    <TD>&nbsp;</TD>
    <TD style="border-right: 2px solid #000000">&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD nowrap align="center" colspan="2"><B>Aggregate</B></TD>
    <TD>&nbsp;</TD>
    <TD style="border-right: 2px solid #000000">&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD nowrap align="center" colspan="2"><B>Registration</B></TD>
    <TD>&nbsp;</TD>
    <TD width="1%">&nbsp;</TD>
</TR>
<TR style="font-size: 8pt" valign="bottom">    <TD width="1%">&nbsp;</TD>

    <TD nowrap align="center"><B>To Be Registered</B></TD>
    <TD style="border-right: 2px solid #000000">&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD nowrap align="center" colspan="2"><B>Registered</B></TD>
    <TD>&nbsp;</TD>
    <TD style="border-right: 2px solid #000000">&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD nowrap align="center" colspan="2"><B>Per Share</B></TD>
    <TD>&nbsp;</TD>
    <TD style="border-right: 2px solid #000000">&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD nowrap align="center" colspan="2"><B>Offering Price</B></TD>
    <TD>&nbsp;</TD>
    <TD style="border-right: 2px solid #000000">&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD nowrap align="center" colspan="2"><B>Fee</B></TD>
    <TD>&nbsp;</TD>
    <TD width="1%">&nbsp;</TD>
</TR>
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<!-- Begin Table Body -->
<TR valign="bottom">
    <TD width="1%" style="border-top: 2px solid #000000">&nbsp;</TD>
    <TD style="border-top: 2px solid #000000"><DIV style="margin-left:15px; text-indent:-15px"><B>common stock,
no par value</B></DIV></TD>
    <TD style="border-right: 2px solid #000000; border-top: 2px solid #000000">&nbsp;</TD>
    <TD style="border-top: 2px solid #000000">&nbsp;</TD>

<TD nowrap colspan="3" align="center" style="border-top: 2px solid #000000"><B>1,700,000&nbsp;shares</B></TD>
    <TD style="border-right: 2px solid #000000; border-top: 2px solid #000000">&nbsp;</TD>
    <TD style="border-top: 2px solid #000000">&nbsp;</TD>
    <TD nowrap align="left" style="border-top: 2px solid #000000"><B>$</B></TD>
    <TD align="right" style="border-top: 2px solid #000000"><B>49.86</B></TD>
    <TD nowrap style="border-top: 2px solid #000000"><B>(1)</B></TD>
    <TD style="border-right: 2px solid #000000; border-top: 2px solid #000000">&nbsp;</TD>
    <TD style="border-top: 2px solid #000000">&nbsp;</TD>
    <TD nowrap align="left" style="border-top: 2px solid #000000"><B>$</B></TD>
    <TD align="right" style="border-top: 2px solid #000000"><B>84,762,000</B></TD>
    <TD nowrap style="border-top: 2px solid #000000"><B>(1)</B></TD>
    <TD style="border-right: 2px solid #000000; border-top: 2px solid #000000">&nbsp;</TD>
    <TD style="border-top: 2px solid #000000">&nbsp;</TD>
    <TD align="left" style="border-top: 2px solid #000000"><B>$</B></TD>
    <TD align="right" style="border-top: 2px solid #000000"><B>9,976.49</B></TD>
    <TD style="border-top: 2px solid #000000">&nbsp;</TD>
    <TD width="1%" style="border-top: 2px solid #000000">&nbsp;</TD>
</TR>
<TR style="font-size: 1px" valign="bottom">
    <TD nowrap align="left" colspan="21" style="border-top: 3px solid #000000">&nbsp;</TD>
</TR>
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</TABLE>
</DIV>

<P>
<TABLE width="100%" border="0" cellpadding="0" cellspacing="0" style="font-size: 10pt">

<TR valign="top" style="font-size: 10pt; color: #000000; background: transparent">
    <TD width="1%" nowrap align="left">(1)&nbsp;&nbsp;</TD>
    <TD>Estimated solely for the purpose of calculating the amount of the registration fee pursuant
to Rule 457(h) promulgated under the Securities Act 1933, as amended (the &#147;Securities Act&#148;). The
price per share and aggregate offering price are based upon $49.86, which is the average of the
high and low sale price of the Company&#146;s common stock as reported on the Nasdaq Stock Market
National Market System for April&nbsp;11, 2005, for 1,700,000 shares reserved for future issuance
pursuant to the 2005 Equity Incentive Plan.</TD>
</TR>

</TABLE>

<DIV style="width: 100%; border-bottom: 1pt solid black; margin-top: 10pt; font-size: 1pt">&nbsp;</DIV>
<DIV style="width: 100%; border-bottom: 2pt solid black; font-size: 1pt">&nbsp;</DIV>

<P align="center" style="font-size: 10pt">&nbsp;
</DIV>

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<DIV style="font-family: 'Times New Roman',Times,serif">

<!-- TOC -->
<A name="toc"><DIV align="CENTER" style="page-break-before:always"><U><B>TABLE OF CONTENTS</B></U></DIV></A>

<P><CENTER>
<TABLE border="0" width="90%" cellpadding="0" cellspacing="0">
<TR>
	<TD width="3%"></TD>
	<TD width="3%"></TD>
	<TD width="3%"></TD>
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	<TD width="76%"></TD>
</TR>
<TR><TD colspan="9"><A HREF="#000">PART II INFORMATION REQUIRED IN THE REGISTRATION STATEMENT</A></TD></TR>
<TR><TD></TD><TD colspan="8"><A HREF="#001">Item&nbsp;3. Incorporation of Documents by Reference.</A></TD></TR>
<TR><TD></TD><TD colspan="8"><A HREF="#002">Item&nbsp;4. Description of Securities.</A></TD></TR>
<TR><TD></TD><TD colspan="8"><A HREF="#003">Item&nbsp;5. Interests of Named Experts and Counsel.</A></TD></TR>
<TR><TD></TD><TD colspan="8"><A HREF="#004">Item&nbsp;6. Indemnification of Directors and Officers.</A></TD></TR>
<TR><TD></TD><TD colspan="8"><A HREF="#005">Item&nbsp;7. Exemption from Registration Claimed.</A></TD></TR>
<TR><TD></TD><TD colspan="8"><A HREF="#006">Item&nbsp;8. Exhibits.</A></TD></TR>
<TR><TD></TD><TD colspan="8"><A HREF="#007">Item&nbsp;9. Undertakings.</A></TD></TR>
<TR><TD colspan="9"><A HREF="#008">Signatures</A></TD></TR>
<TR><TD colspan="9"><A HREF="#009">EXHIBIT INDEX</A></TD></TR>
<TR><TD colspan="9"><A HREF="v07907orexv5w1.txt">EXHIBIT 5.1</A></TD></TR>
<TR><TD colspan="9"><A HREF="v07907orexv23w1.txt">EXHIBIT 23.1</A></TD></TR>
</TABLE>
</CENTER>
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<P><HR noshade><P>
<H5 align="left" style="page-break-before:always"><A HREF="#toc">Table of Contents</A></H5><P>

<!-- link1 "PART II INFORMATION REQUIRED IN THE REGISTRATION STATEMENT" -->
<DIV align="left"><A NAME="000"></A></DIV>

<P align="center" style="font-size: 10pt"><B>PART II</B>

<P align="center" style="font-size: 10pt"><B>INFORMATION REQUIRED IN THE REGISTRATION<BR>
STATEMENT</B>

<!-- link2 "Item&nbsp;3. Incorporation of Documents by Reference." -->
<DIV align="left"><A NAME="001"></A></DIV>

<P align="left" style="font-size: 10pt"><B>Item&nbsp;3. Incorporation of Documents by Reference.</B>

<P align="left" style="font-size: 10pt">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;The following documents filed by F5 Networks, Inc. (the &#147;Company&#148;) with the Securities and
Exchange Commission are incorporated by reference into this Registration Statement:

<P align="left" style="margin-left:3%; font-size: 10pt">(a)&nbsp;Annual Report on Form 10-K for the year ended September&nbsp;30, 2004;

<P align="left" style="margin-left:3%; font-size: 10pt">(b)&nbsp;Quarterly Report on Form 10-Q for the quarter ended December&nbsp;31, 2004;

<P align="left" style="margin-left:3%; font-size: 10pt">(c)&nbsp;Current Reports on Form 8-K filed December&nbsp;20, 2004 and March&nbsp;2, 2005; and

<P align="left" style="margin-left:3%; font-size: 10pt">(d)&nbsp;the description of the Company&#146;s common stock contained in the Company&#146;s Registration
Statement Form 8-A, filed May&nbsp;11, 1999 under the Securities Exchange Act of 1934, as amended
(the &#147;Exchange Act&#148;) including any amendments or reports filed for the purposes of updating
such description.

<P align="left" style="font-size: 10pt">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;All documents subsequently filed by the Company pursuant to Sections&nbsp;13(a), 13(c), 14 or 15(d)
of the Exchange Act, prior to the filing of a post-effective amendment which indicates that all
securities offered have been sold or which deregisters all securities then remaining unsold, shall
be deemed to be incorporated by reference herein and to be part hereof from the date of filing of
such documents.

<!-- link2 "Item&nbsp;4. Description of Securities." -->
<DIV align="left"><A NAME="002"></A></DIV>

<P align="left" style="font-size: 10pt"><B>Item&nbsp;4. Description of Securities.</B>

<P align="left" style="font-size: 10pt">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Not Applicable

<!-- link2 "Item&nbsp;5. Interests of Named Experts and Counsel." -->
<DIV align="left"><A NAME="003"></A></DIV>

<P align="left" style="font-size: 10pt"><B>Item&nbsp;5. Interests of Named Experts and Counsel.</B>

<P align="left" style="font-size: 10pt">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Not Applicable

<!-- link2 "Item&nbsp;6. Indemnification of Directors and Officers." -->
<DIV align="left"><A NAME="004"></A></DIV>

<P align="left" style="font-size: 10pt"><B>Item&nbsp;6. Indemnification of Directors and Officers.</B>

<P align="left" style="font-size: 10pt">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Sections&nbsp;23B.08.500 through 23.B.08.600 of the Washington Business Corporation Act (the
&#147;WBCA&#148;) authorize a court to award, or a corporation&#146;s board of directors to grant, indemnification
to directors and officers on terms sufficiently broad to permit indemnification under certain
circumstances for liabilities arising under the Securities Act of 1933, as amended (the &#147;Securities
Act&#148;). Section&nbsp;23B.08.320 of the WBCA authorizes a corporation to limit a director&#146;s liability to
the corporation or its shareholders for monetary damages for acts or omissions as a director,
except in certain circumstances involving intentional misconduct, knowing violations of law or
illegal corporate loans or distributions, or any transaction from which the director personally
receives a benefit in money, property or services to which the director is not legally entitled.

<P align="left" style="font-size: 10pt">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;The Company&#146;s Second Amended and Restated Articles of Incorporation and Amended and Restated
Bylaws contain provisions permitting the Company to indemnify its directors and officers to the
full extent permitted by Washington law. In addition, the Company&#146;s Second Amended and Restated
Articles of Incorporation contain a provision implementing, to the fullest extent permitted by
Washington law, the above limitations on a director&#146;s liability to the Company and its
shareholders. The Company has entered into certain indemnification agreements with its directors
and certain of its officers, the form of which is attached as Exhibit&nbsp;10.1 to its Registration
Statement on Form S-1 (File No.&nbsp;333-75817). The indemnification agreements provide the Company&#146;s
directors and certain of its officers with indemnification to the maximum extent permitted by the
WBCA. The directors and officers of the Company also may be indemnified against liability they may
incur for serving in that capacity pursuant to a liability insurance policy maintained by the
Company for this purpose.

<P align="center" style="font-size: 10pt">2
</DIV>

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<P><HR noshade><P>
<H5 align="left" style="page-break-before:always"><A HREF="#toc">Table of Contents</A></H5><P>

<DIV style="font-family: 'Times New Roman',Times,serif">
<!-- link2 "Item&nbsp;7. Exemption from Registration Claimed." -->
<DIV align="left"><A NAME="005"></A></DIV>

<P align="left" style="font-size: 10pt"><B>Item&nbsp;7. Exemption from Registration Claimed.</B>

<P align="left" style="font-size: 10pt">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Not Applicable

<!-- link2 "Item&nbsp;8. Exhibits." -->
<DIV align="left"><A NAME="006"></A></DIV>

<P align="left" style="font-size: 10pt"><B>Item&nbsp;8. Exhibits.</B>

<DIV align="center">
<TABLE style="font-size: 10pt" cellspacing="0" border="0" cellpadding="0" width="100%">
<!-- Begin Table Head -->
<TR valign="bottom">
    <TD width="10%">&nbsp;</TD>
    <TD width="5%">&nbsp;</TD>
    <TD width="85%">&nbsp;</TD>
</TR>
<TR style="font-size: 8pt" valign="bottom">
    <TD nowrap align="left" style="border-bottom: 1px solid #000000">Exhibit Number</TD>
    <TD>&nbsp;</TD>
    <TD nowrap align="center" style="border-bottom: 1px solid #000000">Exhibit</TD>
</TR>

<!-- End Table Head -->
<!-- Begin Table Body -->
<TR valign="bottom">
    <TD valign="top" align="center"><DIV style="margin-left:0px; text-indent:-0px">4.1
</DIV></TD>
    <TD>&nbsp;</TD>
    <TD align="left" valign="top">Second Amended and Restated Articles of Incorporation
(Incorporated by reference to Exhibit&nbsp;3.2 to the
Registrant&#146;s Registration Statement on Form&nbsp;S-1, File No.
333-75817).</TD>
</TR>
<TR valign="bottom">
    <TD valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;</DIV></TD>
    <TD>&nbsp;</TD>
    <TD align="left" valign="top">&nbsp;</TD>
</TR>
<TR valign="bottom">
    <TD valign="top" align="center"><DIV style="margin-left:0px; text-indent:-0px">4.2
</DIV></TD>
    <TD>&nbsp;</TD>
    <TD align="left" valign="top">Amended and Restated Bylaws (Incorporated by reference to
Exhibit&nbsp;3.4 to the Registrant&#146;s Registration Statement on
Form&nbsp;S-1, File No.&nbsp;333-75817).</TD>
</TR>
<TR valign="bottom">
    <TD valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;</DIV></TD>
    <TD>&nbsp;</TD>
    <TD align="left" valign="top">&nbsp;</TD>
</TR>
<TR valign="bottom">
    <TD valign="top" align="center"><DIV style="margin-left:0px; text-indent:-0px">4.3
</DIV></TD>
    <TD>&nbsp;</TD>
    <TD align="left" valign="top">Specimen Stock Certificate (Incorporated by reference to
Exhibit&nbsp;4.1 to the Registrant&#146;s Registration Statement on
Form&nbsp;S-1, File No.&nbsp;333-75817).</TD>
</TR>
<TR valign="bottom">
    <TD valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;</DIV></TD>
    <TD>&nbsp;</TD>
    <TD align="left" valign="top">&nbsp;</TD>
</TR>
<TR valign="bottom">
    <TD valign="top" align="center"><DIV style="margin-left:0px; text-indent:-0px">5.1
</DIV></TD>
    <TD>&nbsp;</TD>
    <TD align="left" valign="top">Opinion of Heller Ehrman LLP.</TD>
</TR>
<TR valign="bottom">
    <TD valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;</DIV></TD>
    <TD>&nbsp;</TD>
    <TD align="left" valign="top">&nbsp;</TD>
</TR>
<TR valign="bottom">
    <TD valign="top" align="center"><DIV style="margin-left:0px; text-indent:-0px">10.1
</DIV></TD>
    <TD>&nbsp;</TD>
    <TD align="left" valign="top">2005 Equity Incentive Plan with form of Award Agreement
(Incorporated by reference from Exhibit&nbsp;10.1 to the
Registrant&#146;s Current Report on Form&nbsp;8-K filed on March&nbsp;2,
2005).</TD>
</TR>
<TR valign="bottom">
    <TD valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;</DIV></TD>
    <TD>&nbsp;</TD>
    <TD align="left" valign="top">&nbsp;</TD>
</TR>
<TR valign="bottom">
    <TD valign="top" align="center"><DIV style="margin-left:0px; text-indent:-0px">23.1
</DIV></TD>
    <TD>&nbsp;</TD>
    <TD align="left" valign="top">Consent of PricewaterhouseCoopers LLP, Independent
Registered Public Accounting Firm.</TD>
</TR>
<TR valign="bottom">
    <TD valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;</DIV></TD>
    <TD>&nbsp;</TD>
    <TD align="left" valign="top">&nbsp;</TD>
</TR>
<TR valign="bottom">
    <TD valign="top" align="center"><DIV style="margin-left:0px; text-indent:-0px">23.2
</DIV></TD>
    <TD>&nbsp;</TD>
    <TD align="left" valign="top">Consent of Heller Ehrman LLP (Included in its opinion filed
as Exhibit&nbsp;5.1).</TD>
</TR>
<TR valign="bottom">
    <TD valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;</DIV></TD>
    <TD>&nbsp;</TD>
    <TD align="left" valign="top">&nbsp;</TD>
</TR>
<TR valign="bottom">
    <TD valign="top" align="center"><DIV style="margin-left:0px; text-indent:-0px">24.1
</DIV></TD>
    <TD>&nbsp;</TD>
    <TD align="left" valign="top">Power of Attorney (Included on the signature page of this
Registration Statement).</TD>
</TR>
<!-- End Table Body -->
</TABLE>
</DIV>

<!-- link2 "Item&nbsp;9. Undertakings." -->
<DIV align="left"><A NAME="007"></A></DIV>

<P align="left" style="font-size: 10pt"><B>Item&nbsp;9. Undertakings.</B>

<P align="left" style="font-size: 10pt">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(a)&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;The undersigned Registrant hereby undertakes:

<P align="left" style="font-size: 10pt">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(1)&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;To file, during any period in which offers or sales are being made, a post-effective
amendment to this Registration Statement:

<P align="left" style="font-size: 10pt">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(i)&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;To include any prospectus required by Section&nbsp;10(a)(3) of the Securities Act of 1933;

<P align="left" style="font-size: 10pt">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(ii)&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;To reflect in the prospectus any facts or events arising after the effective date of the
Registration Statement (or the most recent post-effective amendment thereof) which, individually or
in the aggregate, represent a fundamental change in the information set forth in the Registration
Statement;

<P align="left" style="font-size: 10pt">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(iii)&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;To include any material information with respect to the plan of distribution not
previously disclosed in the Registration Statement or any material change to such information in
the Registration Statement;

<P align="center" style="font-size: 10pt">3
</DIV>

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<H5 align="left" style="page-break-before:always"><A HREF="#toc">Table of Contents</A></H5><P>

<DIV style="font-family: 'Times New Roman',Times,serif">
<P align="left" style="font-size: 10pt"><I>Provided, however, </I>that paragraphs (a)(1)(i) and (a)(1)(ii) do not apply if the information
required to be included in a post-effective amendment by those paragraphs is contained in periodic
reports filed by the Registrant pursuant to Section&nbsp;13 or Section 15(d) of the Securities Exchange
Act of 1934 that are incorporated by reference in this Registration Statement.

<P align="left" style="font-size: 10pt">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(2)&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;That, for the purpose of determining any liability under the Securities Act of 1933, each
such post-effective amendment shall be deemed to be a new registration statement relating to the
securities offered therein, and the offering of such securities at that time shall be deemed to be
the initial <I>bona fide </I>offering thereof.

<P align="left" style="font-size: 10pt">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(3)&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;To remove from registration by means of a post-effective amendment any of the securities
being registered which remain unsold at the termination of the offering.

<P align="left" style="font-size: 10pt">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(b)&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;The undersigned Registrant hereby undertakes that, for purposes of determining any
liability under the Securities Act of 1933, each filing of the Registrant&#146;s annual report pursuant
to Section 13(a) or Section 15(d) of the Securities Exchange Act of 1934 that is incorporated by
reference in the Registration Statement shall be deemed to be a new registration statement relating
to the securities offered therein, and the offering of such securities at that time shall be deemed
to be the initial bona fide offering thereof.

<P align="left" style="font-size: 10pt">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(c)&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Insofar as indemnification for liabilities arising under the Securities Act of 1933 may be
permitted to directors, officers and controlling persons of the Registrant pursuant to the
foregoing provisions, or otherwise, the Registrant has been advised that in the opinion of the
Securities and Exchange Commission such indemnification is against public policy as expressed in
the Securities Act of 1933 and is, therefore, unenforceable. In the event that a claim for
indemnification against such liabilities (other than the payment by the Registrant of expenses
incurred or paid by a director, officer or controlling person of the Registrant in the successful
defense of any action, suit or proceeding) is asserted by such director, officer or controlling
person in connection with the securities being registered, the Registrant will, unless in the
opinion of its counsel the matter has been settled by controlling precedent, submit to a court of
appropriate jurisdiction the question of whether such indemnification by it is against public
policy as expressed in the Securities Act of 1933 and will be governed by the final adjudication of
such issue.

<P align="center" style="font-size: 10pt">4
</DIV>

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<P><HR noshade><P>
<H5 align="left" style="page-break-before:always"><A HREF="#toc">Table of Contents</A></H5><P>

<DIV style="font-family: 'Times New Roman',Times,serif">
<!-- link1 "Signatures" -->
<DIV align="left"><A NAME="008"></A></DIV>

<P align="center" style="font-size: 10pt"><B>Signatures</B>

<P align="left" style="font-size: 10pt">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<I>The Registrant</I>. Pursuant to the requirements of the Securities Act of 1933, the Registrant
certifies that it has reasonable grounds to believe that it meets all of the requirements for
filing on Form S-8 and has duly caused this Registration Statement to be signed on its behalf by
the undersigned, thereunto duly authorized, in the City of Seattle, State of Washington, on April
15, 2005.

<TABLE width="100%" border="0" cellspacing="0" cellpadding="0" style="font-size: 10pt">
<TR>
    <TD width="48%">&nbsp;</TD>
    <TD width="1%">&nbsp;</TD>
    <TD width="1%">&nbsp;</TD>
    <TD width="35%">&nbsp;</TD>
    <TD width="15%">&nbsp;</TD>
</TR>
<TR>
    <TD valign="top" align="left">&nbsp;</TD>
    <TD colspan="3" align="left"><B>F5 NETWORKS, INC.</B><BR>
&nbsp;</TD>
    <TD>&nbsp;</TD>
</TR><TR>
    <TD align="left">&nbsp;</TD>
    <TD valign="top">By:&nbsp;&nbsp;</TD>
    <TD colspan="2" align="left">/s/ John McAdam
&nbsp;</TD>
    <TD>&nbsp;</TD>
</TR><TR>
    <TD align="left">&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD colspan="2" align="left">John McAdam, President and&nbsp;</TD>
    <TD>&nbsp;</TD>
</TR><TR>
    <TD align="left">&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD colspan="2" align="left">Chief Executive Officer&nbsp;</TD>
    <TD>&nbsp;</TD>
</TR>
<TR>
    <TD colspan="5">&nbsp;</TD>
</TR>
</TABLE>

<P align="center" style="font-size: 10pt"><B>Power of Attorney</B>

<P align="left" style="font-size: 10pt">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Each person whose signature appears below constitutes and appoints John McAdam or Joann
Reiter, or either of them, his true and lawful attorney-in-fact, with the power of substitution and
resubstitution, for him in his name, place or stead, in any and all capacities, to sign any or all
amendments to this Registration Statement, and to file the same, with exhibits thereto and other
documents in connection therewith, with the Securities and Exchange Commission, hereby ratifying
and confirming all that said attorneys-in-fact and their agents or substitutes, may lawfully do or
lawfully cause to be done by virtue hereof.

<P align="left" style="font-size: 10pt">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Pursuant to the requirements of the Securities Act of 1933, this Registration Statement has
been signed by the following persons in the capacities and on the dates indicated.

<DIV align="center">
<TABLE style="font-size: 10pt" cellspacing="0" border="0" cellpadding="0" width="100%">
<!-- Begin Table Head -->
<TR valign="bottom">
    <TD width="30%">&nbsp;</TD>
    <TD width="5%">&nbsp;</TD>
    <TD width="30%">&nbsp;</TD>
    <TD width="5%">&nbsp;</TD>
    <TD width="30%">&nbsp;</TD>
</TR>
<TR style="font-size: 8pt" valign="bottom">
    <TD nowrap align="left" style="border-bottom: 1px solid #000000">Signature</TD>
    <TD>&nbsp;</TD>
    <TD nowrap align="center" style="border-bottom: 1px solid #000000">Title</TD>
    <TD>&nbsp;</TD>
    <TD nowrap align="center" style="border-bottom: 1px solid #000000">Date</TD>
</TR>

<!-- End Table Head -->
<!-- Begin Table Body -->
<TR valign="bottom">
    <TD valign="top"><DIV style="margin-left:0px; text-indent:-0px">/s/ John McAdam<BR>
John McAdam
</DIV></TD>
    <TD>&nbsp;</TD>
    <TD align="left" valign="top">President, Chief Executive
Officer and Director (Principal
Executive Officer)
</TD>
    <TD>&nbsp;</TD>
    <TD align="center" valign="top">April&nbsp;15, 2005</TD>
</TR>
<TR valign="bottom">
    <TD valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;</DIV></TD>
    <TD>&nbsp;</TD>
    <TD align="left" valign="top">&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD align="left" valign="top">&nbsp;</TD>
</TR>
<TR valign="bottom">
    <TD valign="top"><DIV style="margin-left:0px; text-indent:-0px">/s/ Steven B. Coburn<BR>
Steven B. Coburn
</DIV></TD>
    <TD>&nbsp;</TD>
    <TD align="left" valign="top">Senior Vice President and Chief
Financial Officer (Principal
Financial and Accounting
Officer)
</TD>
    <TD>&nbsp;</TD>
    <TD align="center" valign="top">April&nbsp;15, 2005</TD>
</TR>
<TR valign="bottom">
    <TD valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;</DIV></TD>
    <TD>&nbsp;</TD>
    <TD align="left" valign="top">&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD align="left" valign="top">&nbsp;</TD>
</TR>
<TR valign="bottom">
    <TD valign="top"><DIV style="margin-left:0px; text-indent:-0px">/s/ Gary Ames<BR>
Gary Ames
</DIV></TD>
    <TD>&nbsp;</TD>
    <TD align="left" valign="top">Director
</TD>
    <TD>&nbsp;</TD>
    <TD align="center" valign="top">April&nbsp;15, 2005</TD>
</TR>
<TR valign="bottom">
    <TD valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;</DIV></TD>
    <TD>&nbsp;</TD>
    <TD align="left" valign="top">&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD align="left" valign="top">&nbsp;</TD>
</TR>
<TR valign="bottom">
    <TD valign="top"><DIV style="margin-left:0px; text-indent:-0px">/s/ Keith D. Grinstein<BR>
Keith D. Grinstein
</DIV></TD>
    <TD>&nbsp;</TD>
    <TD align="left" valign="top">Director
</TD>
    <TD>&nbsp;</TD>
    <TD align="center" valign="top">April&nbsp;15, 2005</TD>
</TR>
<TR valign="bottom">
    <TD valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;</DIV></TD>
    <TD>&nbsp;</TD>
    <TD align="left" valign="top">&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD align="left" valign="top">&nbsp;</TD>
</TR>
<TR valign="bottom">
    <TD valign="top"><DIV style="margin-left:0px; text-indent:-0px">/s/ Karl D. Guelich<BR>
Karl D. Guelich
</DIV></TD>
    <TD>&nbsp;</TD>
    <TD align="left" valign="top">Director
</TD>
    <TD>&nbsp;</TD>
    <TD align="center" valign="top">April&nbsp;15, 2005</TD>
</TR>
<TR valign="bottom">
    <TD valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;</DIV></TD>
    <TD>&nbsp;</TD>
    <TD align="left" valign="top">&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD align="left" valign="top">&nbsp;</TD>
</TR>
<TR valign="bottom">
    <TD valign="top"><DIV style="margin-left:0px; text-indent:-0px">/s/ Alan Higginson<BR>
Alan Higginson
</DIV></TD>
    <TD>&nbsp;</TD>
    <TD align="left" valign="top">Director
</TD>
    <TD>&nbsp;</TD>
    <TD align="center" valign="top">April&nbsp;15, 2005</TD>
</TR>
<TR valign="bottom">
    <TD valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;</DIV></TD>
    <TD>&nbsp;</TD>
    <TD align="left" valign="top">&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD align="left" valign="top">&nbsp;</TD>
</TR>
<TR valign="bottom">
    <TD valign="top"><DIV style="margin-left:0px; text-indent:-0px">/s/ Rich Malone<BR>
Rich Malone
</DIV></TD>
    <TD>&nbsp;</TD>
    <TD align="left" valign="top">Director
</TD>
    <TD>&nbsp;</TD>
    <TD align="center" valign="top">April&nbsp;15, 2005</TD>
</TR>
<!-- End Table Body -->
</TABLE>
</DIV>

<P align="center" style="font-size: 10pt">5
</DIV>

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<P><HR noshade><P>
<H5 align="left" style="page-break-before:always"><A HREF="#toc">Table of Contents</A></H5><P>

<DIV style="font-family: 'Times New Roman',Times,serif">

<!-- link1 "EXHIBIT INDEX" -->
<DIV align="left"><A NAME="009"></A></DIV>

<P align="center" style="font-size: 10pt"><U><B>EXHIBIT INDEX</B></U>

<DIV align="center">
<TABLE style="font-size: 10pt" cellspacing="0" border="0" cellpadding="0" width="100%">
<!-- Begin Table Head -->
<TR valign="bottom">
    <TD width="10%">&nbsp;</TD>
    <TD width="5%">&nbsp;</TD>
    <TD width="85%">&nbsp;</TD>
</TR>
<TR style="font-size: 8pt" valign="bottom">
    <TD nowrap align="left" style="border-bottom: 1px solid #000000">Exhibit Number</TD>
    <TD>&nbsp;</TD>
    <TD nowrap align="center" style="border-bottom: 1px solid #000000">Exhibit</TD>
</TR>

<!-- End Table Head -->
<!-- Begin Table Body -->
<TR valign="bottom">
    <TD valign="top" align="center"><DIV style="margin-left:0px; text-indent:-0px">4.1
</DIV></TD>
    <TD>&nbsp;</TD>
    <TD align="left" valign="top">Second Amended and Restated Articles of Incorporation
(Incorporated by reference to Exhibit&nbsp;3.2 to the
Registrant&#146;s Registration Statement on Form&nbsp;S-1, File No.
333-75817).</TD>
</TR>
<TR valign="bottom">
    <TD valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;</DIV></TD>
    <TD>&nbsp;</TD>
    <TD align="left" valign="top">&nbsp;</TD>
</TR>
<TR valign="bottom">
    <TD valign="top" align="center"><DIV style="margin-left:0px; text-indent:-0px">4.2
</DIV></TD>
    <TD>&nbsp;</TD>
    <TD align="left" valign="top">Amended and Restated Bylaws (Incorporated by reference to
Exhibit&nbsp;3.4 to the Registrant&#146;s Registration Statement on
Form&nbsp;S-1, File No.&nbsp;333-75817).</TD>
</TR>
<TR valign="bottom">
    <TD valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;</DIV></TD>
    <TD>&nbsp;</TD>
    <TD align="left" valign="top">&nbsp;</TD>
</TR>
<TR valign="bottom">
    <TD valign="top" align="center"><DIV style="margin-left:0px; text-indent:-0px">4.3
</DIV></TD>
    <TD>&nbsp;</TD>
    <TD align="left" valign="top">Specimen Stock Certificate (Incorporated by reference to
Exhibit&nbsp;4.1 to the Registrant&#146;s Registration Statement on
Form&nbsp;S-1, File No.&nbsp;333-75817).</TD>
</TR>
<TR valign="bottom">
    <TD valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;</DIV></TD>
    <TD>&nbsp;</TD>
    <TD align="left" valign="top">&nbsp;</TD>
</TR>
<TR valign="bottom">
    <TD valign="top" align="center"><DIV style="margin-left:0px; text-indent:-0px">5.1
</DIV></TD>
    <TD>&nbsp;</TD>
    <TD align="left" valign="top">Opinion of Heller Ehrman LLP.</TD>
</TR>
<TR valign="bottom">
    <TD valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;</DIV></TD>
    <TD>&nbsp;</TD>
    <TD align="left" valign="top">&nbsp;</TD>
</TR>
<TR valign="bottom">
    <TD valign="top" align="center"><DIV style="margin-left:0px; text-indent:-0px">10.1
</DIV></TD>
    <TD>&nbsp;</TD>
    <TD align="left" valign="top">2005 Equity Incentive Plan with form of Award Agreement
(Incorporated by reference from Exhibit&nbsp;10.1 to the
Registrant&#146;s Current Report on Form&nbsp;8-K filed on March&nbsp;2,
2005).</TD>
</TR>
<TR valign="bottom">
    <TD valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;</DIV></TD>
    <TD>&nbsp;</TD>
    <TD align="left" valign="top">&nbsp;</TD>
</TR>
<TR valign="bottom">
    <TD valign="top" align="center"><DIV style="margin-left:0px; text-indent:-0px">23.1
</DIV></TD>
    <TD>&nbsp;</TD>
    <TD align="left" valign="top">Consent of PricewaterhouseCoopers LLP, Independent
Registered Public Accounting Firm.</TD>
</TR>
<TR valign="bottom">
    <TD valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;</DIV></TD>
    <TD>&nbsp;</TD>
    <TD align="left" valign="top">&nbsp;</TD>
</TR>
<TR valign="bottom">
    <TD valign="top" align="center"><DIV style="margin-left:0px; text-indent:-0px">23.2
</DIV></TD>
    <TD>&nbsp;</TD>
    <TD align="left" valign="top">Consent of Heller Ehrman LLP (Included in its opinion filed
as Exhibit&nbsp;5.1).</TD>
</TR>
<TR valign="bottom">
    <TD valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;</DIV></TD>
    <TD>&nbsp;</TD>
    <TD align="left" valign="top">&nbsp;</TD>
</TR>
<TR valign="bottom">
    <TD valign="top" align="center"><DIV style="margin-left:0px; text-indent:-0px">24.1
</DIV></TD>
    <TD>&nbsp;</TD>
    <TD align="left" valign="top">Power of Attorney (Included on the signature page of this
Registration Statement).</TD>
</TR>
<!-- End Table Body -->
</TABLE>
</DIV>

<P align="center" style="font-size: 10pt">6
</DIV>

</BODY>
</HTML>
</TEXT>
</DOCUMENT>
<DOCUMENT>
<TYPE>EX-5.1
<SEQUENCE>2
<FILENAME>v07907orexv5w1.txt
<DESCRIPTION>EXHIBIT 5.1
<TEXT>
<PAGE>
                                                             Main (206) 447-0900
                                                              Fax (206) 447-0849
                                                                      25931-0002

                                 April 15, 2005

The Board of Directors
F5 Networks, Inc.
501 Elliott Avenue West
Seattle, Washington 98119

      RE:   REGISTRATION STATEMENT ON FORM S-8

Ladies and Gentlemen:

      This opinion is furnished to F5 Networks, Inc., a Washington corporation
(the "Company"), in connection with the filing of a Registration Statement on
Form S-8 (the "Registration Statement") with the Securities and Exchange
Commission under the Securities Act of 1933, as amended, relating to the
proposed sale by the Company of up to 1,700,000 shares (the "Shares") of common
stock, no par value (the "Common Stock"), issuable by the Company under the 2005
Equity Incentive Plan (the "Plan").

      We have reviewed, among other things, the Company's Articles of
Incorporation and Bylaws, each as amended, the Plan and related agreements and
records of corporate proceedings and other actions taken or proposed to be taken
by the Company in connection with the authorization, issuance and sale of the
Shares pursuant to the Plan. We have made such other factual inquiries as we
deemed necessary to render this opinion.

      Based upon the foregoing and in reliance thereon, it is our opinion that
the reservation for issuance of the Shares pursuant to the Plan has been duly
authorized and, when issued pursuant to the Plan and any related agreements, the
Shares will be validly issued, fully paid and non-assessable.

      We express no opinion herein as to the laws of any state or jurisdiction
other than the State of Washington and the federal laws of the United States.

      We hereby authorize and consent to the use of this opinion as an exhibit
to the Registration Statement and to all references to us in the Registration
Statement and any amendments thereto.

                                        Very truly yours,

                                        /s/ HELLER EHRMAN LLP
</TEXT>
</DOCUMENT>
<DOCUMENT>
<TYPE>EX-23.1
<SEQUENCE>3
<FILENAME>v07907orexv23w1.txt
<DESCRIPTION>EXHIBIT 23.1
<TEXT>
<PAGE>
                                                                    EXHIBIT 23.1

            Consent of Independent Registered Public Accounting Firm

      We hereby consent to the incorporation by reference in this Registration
Statement on Form S-8 of our report dated December 3, 2004 relating to the
consolidated financial statements and financial statement schedule, which
appears in the F5 Networks, Inc. Annual Report on Form 10-K for the year ended
September 30, 2004.

/s/ PricewaterhouseCoopers LLP
Seattle, Washington
April 15, 2005
</TEXT>
</DOCUMENT>
</SUBMISSION>
