8-K

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                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549

                                 ---------------

                                    FORM 8-K

                                 CURRENT REPORT
                     Pursuant to Section 13 or 15(d) of the
                         Securities Exchange Act of 1934


      Date of Report (Date of earliest event reported): DECEMBER 20, 1999



                               CISCO SYSTEMS, INC.
               (Exact name of registrant as specified in charter)



                                                       
         CALIFORNIA                     0-18225                  77-0059951
(State or other jurisdiction          (Commission              (IRS Employer
     of incorporation)                File Number)           Identification No.)


170 WEST TASMAN DRIVE, SAN JOSE, CALIFORNIA                      95134-1706
(Address of principal executive offices)                         (Zip Code)




Registrant's telephone number, including area code: (408) 526-4000

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ITEM 5. OTHER EVENTS

On December 20, 1999 Cisco Systems, Inc. ("Cisco") announced a definitive
agreement to acquire the optical systems business of Pirelli S.p.A ("Pirelli")
of Milan, Italy, pursuant to an Share Purchase Agreement dated as of December
20, 1999 (the "Agreement"), by and among Cisco, Pirelli and certain affiliates
of Cisco and Pirelli.


ITEM 7. FINANCIAL STATEMENTS, PRO FORMA FINANCIAL INFORMATION AND EXHIBITS

     (a)  Exhibits.



Exhibit No.    Description
            

   99.1        Press Release of Registrant, dated December 20, 1999, announcing
               the definitive agreement to acquire the optical systems business
               of Pirelli S.p.A.


                  [Remainder of page intentionally left blank]

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                                   SIGNATURES

     Pursuant to the requirements of the Securities Exchange Act of 1934, as
amended, the Registrant has duly caused this report to be signed on its behalf
by the undersigned hereunto duly authorized.



                                      CISCO SYSTEMS, INC.



Dated: December 20, 1999              By: /s/ LARRY R. CARTER
                                         -------------------------------------
                                         Larry R. Carter, Senior Vice President,
                                         Finance and Administration,
                                         Chief Financial Officer and Secretary


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                                  EXHIBIT INDEX



Exhibit
Number         Description of Document
- -------        -----------------------
            

   99.1        Press Release of Registrant, dated December 20, 1999, announcing
               the definitive agreement to acquire the optical systems business
               of Pirelli S.p.A.

EX-99.1

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                                                                    Exhibit 99.1

CISCO SYSTEMS TO ACQUIRE PIRELLI OPTICAL SYSTEMS
CISCO'S ENTRY INTO DWDM MARKET BOLSTERS ITS OPTICAL NETWORKING PORTFOLIO

     SAN JOSE, Calif., Dec. 20, 1999 -- Cisco Systems, Inc. today announced a
definitive agreement to acquire the optical systems business of Pirelli S.p.A of
Milan, Italy. Pirelli is a recognized innovator in both optical component
technology and optical systems for service providers. The purchase of Pirelli
Optical Systems is Cisco's first multi-billion dollar acquisition in Europe and
Cisco's first entry into the dense wave division multiplexing (DWDM) market.
DWDM is an innovative technology that uses different color light waves instead
of electronic pulses to dramatically increase the capacity of broadband networks
carrying a combination of phone, Internet, and video traffic.

     In connection with this acquisition, Cisco also announced a strategic
alliance with Pirelli S.p.A. and that it intends to invest $100 million in
Pirelli's optical components and submarine optical transmission system
businesses. Under the terms of the agreement, Cisco is acquiring Pirelli Optical
Systems for an aggregate consideration of up to $2.15 billion of which a portion
is contingent on revenue targets and other performance milestones. The
transaction will be accounted for using purchase accounting. In connection with
the acquisition, Cisco expects a one-time charge against after-tax earnings
between $0.03 to $0.09 per share for purchased in-process research and
development expenses in the third quarter of fiscal 2000. This acquisition has
been approved by the board of directors of each company and is subject to
various closing conditions including approval under the Hart-Scott-Rodino
Antitrust Improvements Act and certain country antitrust reviews.

     The acquisition of Pirelli Optical Systems enables Cisco to offer an
end-to-end optical networking solution for service providers. Pirelli's optical
products will be seamlessly integrated with optical products and technology that
Cisco has acquired from start-ups Cerent, Monterey Networks and Pipelinks. When
these optical acquisitions are combined with Cisco's leadership in Internet
routing, the acquisition of Pirelli's optical business allows Cisco to
immediately address the total optical networking market estimated to be over $40
billion by 2005.

     "Pirelli's optical business delivers innovative technology and systems from
an early stage company and provides Cisco with additional European channel and
sales support," said Don Listwin Cisco executive VP, service provider and
consumer lines of business. "With this capability, Cisco becomes the only
company in the world capable of delivering an end-to-end 10 gigabit--or OC-192--
Internet based optical network."

     Pirelli Optical Systems is the first company to ship open standards-based,
10 gigabits per second (Gbps; also known as OC-192) optical transport systems
and its products represent the largest installed base of such products in the
world. Pirelli Optical Systems' OC-192 systems represent the most advanced
high-speed fiber optic technology used in next-generation optical networks.
Leading U.S. and international service providers such as Frontier/Global
Crossing, Telecom Brazil , France Telecom and Deutsche Telecom have deployed
Pirelli's DWDM technology.

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     The company's technology will be integrated into Cisco's current optical
product family and will provide a foundation for future Internet-based, optical
solutions in this market. This acquisition addresses the fourth phase in Cisco's
five-phase optical transport strategy and will provide Cisco with additional
optical transport expertise in Europe including a sales team and sales support
for Cisco's European customers.

     Pirelli Optical Systems' strong technical team strengthens Cisco's newly
created optical product group led by Cisco group vice president Carl Russo.
Pirelli's systems business was founded in 1995. The 701 employees located
primarily in Milan, Italy; Tregastal, France; Wuppertal, Germany and Lexington,
South Carolina will be led by Pirelli Optical Systems' current CEO Geraint
Anderson and will join Cisco's optical product group in the service provider
line of business.

EDITORS NOTE

     Cisco will hold a conference call for press and analysts on December 20
1999 at 5:30 a.m. PST. Domestic call-in number: (888) 937-3225, International
call-in number: (415) 908-4755. A replay of the conference call will be
available at 7:30 a.m. PST on 12/20/99 and can be accessed with reservation
#13890493. Domestic call-in number: (800) 633-8284; international call in
number: (858) 812-6440. It is also available on Cisco's Web site at
www.cisco.com under Investor Information.

CISCO SYSTEMS

CISCO SYSTEMS, INC. (NASDAQ:CSCO) is the worldwide leader in networking for the
Internet.

CONTACT FOR THIS PRESS RELEASE:

Abby Smith
Cisco Systems, Inc.
(408) 525-8548
absmith@cisco.com

Imogen Bailey
Cisco Systems, Inc.
+44 181 756 8219
imbailey@cisco.com
For more information visit Cisco PR Contacts

                                      # # #

     This release may contain projections or other forward-looking statements
regarding future events or the future financial performance of the Company that
involve risks and uncertainties. Readers are cautioned that these statements are
only predictions and may differ materially from actual future events or results.
Readers are referred to the documents filed by Cisco with the SEC, specifically
the most recent reports on Form 10-K and 10-Q, which identify important risk
factors that could cause actual results to differ from those contained in the
forward-looking statements, including risks associated with acquisition
strategy, dependence on new product offerings, competition, patents,
intellectual property and licensing, future growth,

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rapid technological and market change, manufacturing and sourcing risks,
Internet infrastructure and regulation, international operations, volatility of
stock price, financial risk management and potential volatility in operating
results, among others.

     Cisco, Cisco IOS, Cisco Systems, Catalyst, and the Cisco Systems logo are
registered trademarks of Cisco Systems, Inc. in the U.S. and certain other
countries. All other trademarks mentioned in this document are the property of
their respective owners. The use of the word partner does not imply a
partnership relationship between Cisco and any of its resellers. (9907R)