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                                    EXHIBIT 5

             OPINION AND CONSENT OF BROBECK, PHLEGER & HARRISON LLP


                               February 15, 2001


Cisco Systems, Inc.
170 West Tasman Drive
San Jose, California 95134-1706

               Re:    Cisco Systems, Inc. -- Registration Statement for
                      Offering of 1,725,112 Shares of Common Stock

Dear Ladies and Gentlemen:

               We have acted as counsel to Cisco Systems, Inc., a California
corporation (the "Company"), in connection with the registration on Form S-8
(the "Registration Statement") under the Securities Act of 1933, as amended, of
1,725,112 shares of common stock (the "Shares") and related stock options under
the Active Voice Corporation 1988 Non-qualified Stock Option Plan, 1993 Stock
Option Plan, 1996 Stock Option Plan, 1998 Stock Option Plan, and 2000 Stock
Option Plan (together, the "Plans").

               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 in connection with the assumption of
the Plans and the outstanding options thereunder. Based on such review, we are
of the opinion that if, as and when the Shares are issued and sold (and the
consideration therefor received) pursuant to the provisions of option agreements
duly authorized under the Plans 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 Plans or the Shares.


                                Very truly yours,


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



