As filed with the Securities and Exchange Commission on January 14, 2005 

                                                    Registration No. 333-
                                                       

                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549

                                    FORM S-8
                             REGISTRATION STATEMENT
                                      UNDER
                           THE SECURITIES ACT OF 1933

                                F5 NETWORKS, INC.
             (Exact Name of Registrant as Specified in Its Charter)

                                   Washington
                          (State or Other Jurisdiction
                        of Incorporation or Organization)

                                   91-1714307
                      (I.R.S. Employer Identification No.)

               401 Elliott Avenue West, Seattle, Washington     98119
               (Address of Principal Executive Offices)       (Zip Code)

                   MagniFire Acquisition Equity Incentive Plan
                       NonQualified Stock Option Agreement
                            (Full Title of the Plan)

                                  Joann Reiter
                                F5 Networks, Inc.
                             401 Elliott Avenue West
                                Seattle, WA 98119
                     (Name and Address of Agent for Service)

                                 (206) 272-5555
          (Telephone Number, Including Area Code, of Agent for Service)

                         CALCULATION OF REGISTRATION FEE

================== ================== ==================== ====================

                                                     Proposed
    Title of                     Proposed Maximum     Maximum         Amount of
   Securities     Amount To Be    Offering Price     Aggregate      Registration
     To Be         Registered        Per Share      Offering Price        Fee
   Registered                                                                  
---------------- --------------- ----------------- ----------------- ----------
 common stock,    715,000 shares      $42.54(1)      $30,417,530(1)    $3,580.14
 no par value
---------------- --------------- ----------------- ------------------ ----------
(1)      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  "Securities  Act"). The price per
         share and aggregate offering price are based upon $42.54,  which is the
         average of the high and low sale price of the Company's common stock as
         reported on the Nasdaq Stock Market  National Market System for January
         12, 2005, for (a) 415,000 shares reserved for future issuance  pursuant
         to the MagniFire  Acquisition  Equity  Incentive  Plan, and (b) 300,000
         shares  reserved for future issuance  pursuant to a NonQualified  Stock
         Option Agreement.



                                     PART II

                    INFORMATION REQUIRED IN THE REGISTRATION
                                    STATEMENT

Item 3.  Incorporation of Documents by Reference.

         The following documents filed by F5 Networks, Inc. (the "Company") with
the Securities and Exchange  Commission are  incorporated by reference into this
Registration Statement:

(a)      Annual Report on Form 10-K for the year ended September 30, 2004; and

(b)      the  description  of  the  Company's  common  stock  contained  in  the
         Company's Registration Statement Form 8-A, filed May 11, 1999 under the
         Securities  Exchange  Act of 1934,  as  amended  (the  "Exchange  Act")
         including any  amendments or reports filed for the purposes of updating
         such description.

         All documents  subsequently  filed by the Company  pursuant to Sections
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.

Item 4.  Description of Securities.

         Not Applicable

Item 5.  Interests of Named Experts and Counsel.

         Not Applicable

Item 6.  Indemnification of Directors and Officers.

         Sections  23B.08.500  through  23.B.08.600 of the  Washington  Business
Corporation  Act (the  "WBCA")  authorize a court to award,  or a  corporation'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
"Securities  Act").  Section  23B.08.320 of the WBCA authorizes a corporation to
limit a director'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.

         The Company'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'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'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 10.1 to its Registration  Statement on Form
S-1 (File No. 333-75817).  The indemnification  agreements provide the Company'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.

Item 7.  Exemption from Registration Claimed.

         Not Applicable

                                       2


Item 8.  Exhibits.

 Exhibit
 Number                               Exhibit

   4.1   Second Amended and Restated Articles of Incorporation (Incorporated
         by reference to Exhibit 3.2 to the Registrant's Registration Statement
         on Form S-1, File No. 333-75817).

   4.2   Amended and Restated Bylaws (Incorporated by reference to Exhibit
         3.4 to the Registrant's Registration Statement on Form S-1, File No.
         333-75817).

   4.3   Specimen Stock Certificate (Incorporated by reference to Exhibit 4.1 to
         the Registrant's Registration Statement on Form S-1, File No.333-
         75817).

   5.1   Opinion of Heller Ehrman White & McAuliffe LLP.

  10.1   MagniFire Acquisition Equity Incentive Plan (Incorporated by
         reference to Exhibit 10.22 to the Registrant's Annual Report on Form
         10-K for the fiscal year ended September 30, 2004).

  10.2   NonQualified Stock Option Agreement between Karl Triebes and the
         Registrant dated August 16, 2004  (Incorporated by reference to Exhibit
         10.23 to the Registrant's Annual Report on Form 10-K for the fiscal
         year ended September 30, 2004).

  23.1   Consent of PricewaterhouseCoopers LLP, Independent Registered Public
         Accounting Firm.

  23.2   Consent of Heller Ehrman White & McAuliffe LLP (Included in its
         opinion filed as Exhibit 5.1).

  24.1   Power of Attorney (Included on the signature page of this Registration
         Statement).


Item 9.  Undertakings.

         (a) The undersigned Registrant hereby undertakes:

                  (1) To file,  during any  period in which  offers or sales are
being made, a post-effective amendment to this Registration Statement:

                           (i) To include  any  prospectus  required  by Section
10(a)(3) of the Securities Act of 1933;

                           (ii) 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;

                                       3



                           (iii)  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;

         Provided,  however,  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 13 or Section 15(d) of the  Securities  Exchange Act of 1934
that are incorporated by reference in this Registration Statement.

                  (2) 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 bona fide offering thereof.

                  (3) 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.

         (b) The undersigned  Registrant hereby undertakes that, for purposes of
determining  any liability  under the Securities Act of 1933, each filing of the
Registrant'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.

         (c)  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.

                                       4


                                   Signatures

         The Registrant.  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 January 14,
2005.

                                       F5 NETWORKS, INC.

                                       By: /s/ John McAdam
                                       John McAdam, President and
                                       Chief Executive Officer

                                Power of Attorney

         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.

         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.

   Signature                     Title                               Date

/s/ John McAdam             President, Chief Executive Officer
John McAdam                 and Director 
                            (Principal Executive Officer)       January 14, 2005

/s/ Steven B. Coburn        Senior Vice President
Steven B. Coburn            and Chief Financial Officer
                            (Principal Financial 
                            and Accounting Officer)             January 14, 2005
                            Officer)

/s/ Gary Ames               Director
Gary Ames                                                       January 14, 2005
 
/s/ Keith D. Grinstein      Director
Keith D. Grinstein                                              January 14, 2005

/s/ Karl D. Guelich         Director
Karl D. Guelich                                                 January 14, 2005

/s/ Alan Higginson          Director
Alan Higginson                                                  January 14, 2005

/s/ Rich Malone             Director
Rich Malone                                                     January 14, 2005


                                       5



                                  EXHIBIT INDEX



 Exhibit 
 Number                               Exhibit

   4.1   Second Amended and Restated Articles of Incorporation (Incorporated
         by reference to Exhibit 3.2 to the Registrant's Registration Statement
         on Form S-1, File No. 333-75817).

   4.2   Amended and Restated Bylaws (Incorporated by reference to Exhibit
         3.4 to the Registrant's Registration Statement on Form S-1, File No.
         333-75817).

   4.3   Specimen Stock Certificate (Incorporated by reference to Exhibit 4.1 to
         the Registrant's Registration Statement on Form S-1, File No.333-
         75817).

   5.1   Opinion of Heller Ehrman White & McAuliffe LLP.

  10.1   MagniFire Acquisition Equity Incentive Plan (Incorporated by
         reference to Exhibit 10.22 to the Registrant's Annual Report on Form
         10-K for the fiscal year ended September 30, 2004).

  10.2   NonQualified Stock Option Agreement between Karl Triebes and the
         Registrant dated August 16, 2004  (Incorporated by reference to Exhibit
         10.23 to the Registrant's Annual Report on Form 10-K for the fiscal
         year ended September 30, 2004).

  23.1   Consent of PricewaterhouseCoopers LLP, Independent Registered Public
         Accounting Firm.

  23.2   Consent of Heller Ehrman White & McAuliffe LLP (Included in its
         opinion filed as Exhibit 5.1).

  24.1   Power of Attorney (Included on the signature page of this Registration
         Statement).