EXHIBIT 5

             OPINION AND CONSENT OF BROBECK, PHLEGER & HARRISON LLP


                               November 20, 2001


Network Appliance, Inc.
495 East Java Drive
Sunnyvale, CA 94089

               Re:    Network Appliance, Inc. - Registration Statement for
                      Offering of an Aggregate of 16,400,000 Shares of Common
                      Stock

Dear Ladies and Gentlemen:

               We have acted as counsel to Network Appliance, Inc., a Delaware
corporation (the "Company"), in connection with the registration on Form S-8
(the "Registration Statement") under the Securities Act of 1933, as amended, of
(a) an additional 13,400,000 shares of Company's common stock reserved for
issuance under the Company's 1999 Stock Option Plan (the "Option Plan") and (b)
an additional 3,000,000 shares of the Company's common stock reserved for
issuance under the Company's Employee Stock Purchase Plan (the "Purchase Plan").

               This opinion is being furnished in accordance with the
requirements of Item 8 of Form S-8 and Item 601(b)(5)(i) of Regulation S-K.

               We have reviewed the Company's charter documents and the
corporate proceedings taken by the Company with respect to the establishment and
amendment of the Option Plan and the Purchase Plan. Based on such review, we are
of the opinion that, if, as and when the shares of the Company's common stock
are issued and sold (and the consideration therefor received) pursuant to (a)
the provisions of (a) stock option agreements duly authorized under the Option
Plan and in accordance with the Registration Statement and (b) stock purchase
rights duly authorized under the Purchase Plan and in accordance with the
Registration Statement, such shares will be duly authorized, legally issued,
fully paid and nonassessable.

               We consent to the filing of this opinion letter as Exhibit 5 to
the Registration Statement.

               This opinion letter is rendered as of the date first written
above and we disclaim any obligation to advise you of facts, circumstances,
events or developments which hereafter may be brought to our attention and which
may alter, affect or modify the opinion expressed herein. Our opinion is
expressly limited to the matters set forth above and we render no opinion,
whether by implication or otherwise, as to any other matters relating to the
Company, the Option Plan, the Purchase Plan or the shares of the Company's
common stock issuable under such plans.

                                             Very truly yours,


                                             /s/ Brobeck, Phleger & Harrison LLP
                                             BROBECK, PHLEGER & HARRISON LLP