<PAGE>   1



   AS FILED WITH THE SECURITIES AND EXCHANGE COMMISSION ON DECEMBER 22, 1998.

                                                   Registration No. 333-________
================================================================================

                       SECURITIES AND EXCHANGE COMMISSION
                              WASHINGTON, DC 20549

                                   ----------

                                    FORM S-8

                             REGISTRATION STATEMENT
                                      UNDER
                           THE SECURITIES ACT OF 1933

                                   ----------

                               FORE SYSTEMS, INC.
             (Exact Name of Registrant as Specified in Its Charter)

<TABLE>
<S>                                                                       <C>       
                       DELAWARE                                                        25-1628117
(State or Other Jurisdiction of Incorporation or Organization)            (I.R.S. Employer Identification No.)

                   1000 FORE DRIVE
               WARRENDALE, PENNSYLVANIA                                                15086-7502
        (Address of Principal Executive Offices)                                       (Zip Code)
</TABLE>


                  FORE SYSTEMS, INC. 1995 STOCK INCENTIVE PLAN
                            (Full Title of the Plan)


                                 THOMAS J. GILL
                      PRESIDENT AND CHIEF EXECUTIVE OFFICER
                               FORE SYSTEMS, INC.
                                 1000 FORE DRIVE
                       WARRENDALE, PENNSYLVANIA 15086-7502
                     (Name and Address of Agent for Service)

                                 (724) 742-4444
          (Telephone Number, Including Area Code, of Agent for Service)

                                   ----------

                         COPY OF ALL COMMUNICATIONS TO:

                             CHRISTOPHER H. GEBHARDT
                 VICE PRESIDENT, CORPORATE COUNSEL AND SECRETARY
                               FORE SYSTEMS, INC.
                                 1000 FORE DRIVE
                       WARRENDALE, PENNSYLVANIA 15086-7502
                                 (724) 742-7658

                                   ----------

                         CALCULATION OF REGISTRATION FEE

<TABLE>
<CAPTION>
====================================================================================================================================

                                                AMOUNT           PROPOSED MAXIMUM         PROPOSED MAXIMUM
                                                 TO BE            OFFERING PRICE         AGGREGATE OFFERING         AMOUNT OF
  TITLE OF SECURITIES TO BE REGISTERED        REGISTERED           PER SHARE (1)             PRICE (1)         REGISTRATION FEE (1)
------------------------------------------------------------------------------------------------------------------------------------
<S>                                         <C>                  <C>                     <C>                   <C>
Common Stock, par value $.01 per share
1995 Stock Incentive Plan                   249,238 shares          $17.625                 $4,392,820               $1,296
====================================================================================================================================
</TABLE>

 (1)  Estimated solely for the purpose of calculating the registration fee
      pursuant to Rule 457(h). The fee is calculated on the basis of the average
      of the high and low sale prices of the registrant's Common Stock reported
      on the Nasdaq National Market on December 15, 1998.

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

<PAGE>   2




This Registration Statement on Form S-8 (the "Registration Statement") of FORE
Systems, Inc. (the "Company") relates to the registration of the issuance and
sale of up to an aggregate of 249,238 shares of the Company's Common Stock, par
value $.01 per share ("Common Stock"), pursuant to the Company's 1995 Stock
Incentive Plan (the "Plan"). A registration statement on Form S-8 (File No.
33-99350) (the "November Registration Statement") with respect to the issuance
and sale of up to an aggregate of 5,600,000 shares of Common Stock issuable
under the Plan was filed with the Securities and Exchange Commission (the
"Commission") on November 14, 1995 and is currently effective. A registration
statement on Form S-8 (File No. 333-4052) (the "April Registration Statement")
with respect to the issuance and sale of up to an aggregate of 3,383,700 shares
of Common Stock issuable under the Plan was filed with the Commission on April
24, 1996 and is currently effective. A registration statement on Form S-8 (File
No. 333-47483) (the "March Registration Statement") with respect to the issuance
and sale of up to an aggregate of 968,986 shares of Common Stock issuable under
the Plan was filed with the Commission on March 6, 1998 and is currently
effective. The contents of the November Registration Statement, the April
Registration Statement and the March Registration Statement are hereby
incorporated by reference into this Registration Statement.


                                     PART II

               INFORMATION REQUIRED IN THE REGISTRATION STATEMENT


ITEM 3.   INCORPORATION OF DOCUMENTS BY REFERENCE.

         In addition to the documents incorporated by reference into the
November Registration Statement, the April Registration Statement and the March
Registration Statement, the following documents filed with the Commission are
incorporated by reference into this Registration Statement:

         1. The Company's Annual Report on Form 10-K, filed with the Commission
for the fiscal year ended March 31, 1998 (No. 0-24156);

         2. The Company's Quarterly Report on Form 10-Q, filed with the
Commission for the quarterly period ended June 30, 1998 (No. 0-24156);

         3. The Company's Quarterly Report on Form 10-Q, filed with the
Commission for the quarterly period ended September 30, 1998 (No. 0-24156);

         4. The Company's Current Report on Form 8-K, dated September 11, 1998;

         5. The Company's Current Report on Form 8-K/A Amendment No. 1, dated
September 11, 1998; and

         6. The Company's Current Report on Form 8-K, dated October 1, 1998.

         All documents subsequently filed by the Company with the Commission
pursuant to Sections 13(a), 13(c), 14 and 15(d) of the Exchange Act after the
date of this Registration Statement, but prior to the filing of a post-effective
amendment to this Registration Statement which indicates that all securities
offered by this Registration Statement have been sold or which deregisters all
such securities then remaining unsold, shall be deemed to be incorporated by
reference into this Registration Statement. Each document incorporated by
reference into this Registration Statement shall be deemed to be a part of this
Registration Statement from the date of the filing of such document with the
Commission until the information contained therein is superseded or updated by
any subsequently filed document which is incorporated by reference into this
Registration Statement or by any document which constitutes part of the
prospectus relating to the Plan meeting the requirements of Section 10(a) of the
Securities Act of 1933, as amended (the "Securities Act").




                                      II-1
<PAGE>   3



ITEM 5.   INTERESTS OF NAMED EXPERTS AND COUNSEL.

         The validity of the shares of Common Stock to be issued under this
Registration Statement will be passed upon for the Company by Morgan, Lewis &
Bockius LLP, Pittsburgh, Pennsylvania. As of December 22, 1998, Marlee S. Myers,
a partner of Morgan, Lewis & Bockius LLP, held options to acquire up to 40,000
shares of Common Stock.


ITEM 8.   EXHIBITS.

         The following exhibits are filed herewith or incorporated by reference
as part of this Registration Statement:

<TABLE>
<CAPTION>
  EXHIBIT NO.                                                 DESCRIPTION
-----------------     --------------------------------------------------------------------------------------------

<S>                   <C>                                                  
      4.1             Amended and Restated Certificate of Incorporation of FORE Systems, Inc. (as amended by
                      Certificate of Amendment dated May 6, 1996) (incorporated by reference to Exhibit 3.1 to the
                      Company's Annual Report on Form 10-K for the fiscal year ended March 31, 1996).

      4.2             Second Amended and Restated By-Laws of FORE Systems, Inc. (as amended through March 5, 1997)
                      (incorporated by reference to Exhibit 3.2 to the Company's Annual Report on Form 10-K for
                      the fiscal year ended March 31, 1997).

      4.3             FORE Systems, Inc. 1995 Stock Incentive Plan (incorporated by reference to Exhibit 4.3 to
                      the Company's Registration Statement on Form S-8 (File No. 33-99350)).

      5.1             Opinion of Morgan, Lewis & Bockius LLP as to the legality of the shares being registered.

      23.1            Consent of PricewaterhouseCoopers LLP, independent accountants.

      23.2            Consent of Morgan, Lewis & Bockius LLP (included in opinion filed as Exhibit 5.1).

      24.1            Power of Attorney (set forth on the signature page of this Registration Statement).
</TABLE>




                                      II-2
<PAGE>   4




                                   SIGNATURES

         Pursuant to the requirements of the Securities Act, 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 Borough of Warrendale, Commonwealth of Pennsylvania, on
December 22, 1998.

                                 FORE Systems, Inc.



                                 By: /s/ Thomas J. Gill                      
                                     ----------------------------
                                     Thomas J. Gill
                                     President and Chief Executive Officer

         KNOW ALL MEN BY THESE PRESENTS, that each of the undersigned directors
and officers of FORE Systems, Inc. hereby constitutes and appoints Thomas J.
Gill and Bruce E. Haney, and each of them, his true and lawful attorneys-in-fact
and agents, for him and in his name, place and stead, in any and all capacities,
to sign one or more amendments to this Registration Statement on Form S-8 under
the Securities Act, including post-effective amendments and other related
documents, and to file the same with the Commission under said Act, hereby
granting power and authority to do and perform any and all acts and things
requisite and necessary to be done in and about the premises, as fully as to all
intents and purposes as he might or could do in person, hereby ratifying and
confirming all that said attorneys-in-fact and agents may lawfully do or cause
to be done by virtue hereof.

         Pursuant to the requirements of the Securities Act, this Registration
Statement and the foregoing Power of Attorney have been signed by the following
persons in the capacities and on the date(s) indicated:

<TABLE>
<CAPTION>
              Signature                                        Title                                  Date
              ---------                                        -----                                  ----


<S>                                        <C>                                                  <C> 
/s/ Eric C. Cooper                         Chairman and a Director                              December 22, 1998
--------------------------------
Eric C. Cooper

/s/ Thomas J. Gill                         President and Chief Executive Officer                December 22, 1998
--------------------------------           (Principal Executive Officer) and a Director
Thomas J. Gill                             

/s/ Robert D. Sansom                       Senior Vice President and Chief Technical            December 22, 1998
--------------------------------           Officer and a Director
Robert D. Sansom                           

/s/ Bruce E. Haney                         Senior Vice President and Chief Financial            December 22, 1998
--------------------------------           Officer (Principal Financial Officer)
Bruce E. Haney                             

/s/ Gary J. Brunner                        Vice President, Controller and Treasurer             December 22, 1998
--------------------------------           (Principal Accounting Officer)
Gary J. Brunner                            

/s/ John C. Baker                          Director                                             December 22, 1998
--------------------------------
John C. Baker

/s/ Daniel W. McGlaughlin                  Director                                             December 22, 1998
--------------------------------
Daniel W. McGlaughlin

/s/ Daniel R. Hesse                        Director                                             December 22, 1998
--------------------------------
Daniel R. Hesse

/s/ John T. LaMacchia                      Director                                             December 22, 1998
--------------------------------
John T. LaMacchia
</TABLE>

<PAGE>   5




                                  EXHIBIT INDEX


<TABLE>
<CAPTION>
  EXHIBIT NO.                                                 DESCRIPTION
-----------------     --------------------------------------------------------------------------------------------

<S>                   <C>                                            
      4.1             Amended and Restated Certificate of Incorporation of FORE Systems, Inc. (as amended by
                      Certificate of Amendment dated May 6, 1996) (incorporated by reference to Exhibit 3.1 to the
                      Company's Annual Report on Form 10-K for the fiscal year ended March 31, 1996).

      4.2             Second Amended and Restated By-Laws of FORE Systems, Inc. (as amended through March 5, 1997)
                      (incorporated by reference to Exhibit 3.2 to the Company's Annual Report on Form 10-K for
                      the fiscal year ended March 31, 1997).

      4.3             FORE Systems, Inc. 1995 Stock Incentive Plan (incorporated by reference to Exhibit 4.3 to
                      the Company's Registration Statement on Form S-8 (File No. 33-99350)).

      5.1             Opinion of Morgan, Lewis & Bockius LLP as to the legality of the shares being registered.

      23.1            Consent of PricewaterhouseCoopers LLP, independent accountants.

      23.2            Consent of Morgan, Lewis & Bockius LLP (included in opinion filed as Exhibit 5.1).

      24.1            Power of Attorney (set forth on the signature page of this Registration Statement).
</TABLE>
[{"type": "S-8", "sequence": "1", "description": "FORE SYSTEMS, INC.", "secsgml_size_bytes": 15314}]
{"company-data": {"conformed-name": "FORE SYSTEMS INC /DE/", "cik": "0000920000", "assigned-sic": "3576", "irs-number": "251628117", "state-of-incorporation": "DE", "fiscal-year-end": "0331"}, "filing-values": {"form-type": "S-8", "act": "33", "file-number": "333-69521", "film-number": "98774054"}, "business-address": {"street1": "1000 FORE DRIVE", "city": "WARRENDALE", "state": "PA", "zip": "15086-7502", "phone": "7247424444"}, "mail-address": {"street1": "1000 FORE DRIVE", "city": "WARRENDALE", "state": "PA", "zip": "15086-7502"}}
1

   AS FILED WITH THE SECURITIES AND EXCHANGE COMMISSION ON DECEMBER 22, 1998.

                                                   Registration No. 333-________
================================================================================

                       SECURITIES AND EXCHANGE COMMISSION
                              WASHINGTON, DC 20549

                                   ----------

                                    FORM S-8

                             REGISTRATION STATEMENT
                                      UNDER
                           THE SECURITIES ACT OF 1933

                                   ----------

                               FORE SYSTEMS, INC.
             (Exact Name of Registrant as Specified in Its Charter)
DELAWARE                                                        25-1628117
(State or Other Jurisdiction of Incorporation or Organization)            (I.R.S. Employer Identification No.)

                   1000 FORE DRIVE
               WARRENDALE, PENNSYLVANIA                                                15086-7502
        (Address of Principal Executive Offices)                                       (Zip Code)
FORE SYSTEMS, INC. 1995 STOCK INCENTIVE PLAN
                            (Full Title of the Plan)

                                 THOMAS J. GILL
                      PRESIDENT AND CHIEF EXECUTIVE OFFICER
                               FORE SYSTEMS, INC.
                                 1000 FORE DRIVE
                       WARRENDALE, PENNSYLVANIA 15086-7502
                     (Name and Address of Agent for Service)

                                 (724) 742-4444
          (Telephone Number, Including Area Code, of Agent for Service)

                                   ----------

                         COPY OF ALL COMMUNICATIONS TO:

                             CHRISTOPHER H. GEBHARDT
                 VICE PRESIDENT, CORPORATE COUNSEL AND SECRETARY
                               FORE SYSTEMS, INC.
                                 1000 FORE DRIVE
                       WARRENDALE, PENNSYLVANIA 15086-7502
                                 (724) 742-7658

                                   ----------

                         CALCULATION OF REGISTRATION FEE
====================================================================================================================================

                                                AMOUNT           PROPOSED MAXIMUM         PROPOSED MAXIMUM
                                                 TO BE            OFFERING PRICE         AGGREGATE OFFERING         AMOUNT OF
  TITLE OF SECURITIES TO BE REGISTERED        REGISTERED           PER SHARE (1)             PRICE (1)         REGISTRATION FEE (1)
------------------------------------------------------------------------------------------------------------------------------------
Common Stock, par value $.01 per share
1995 Stock Incentive Plan                   249,238 shares          $17.625                 $4,392,820               $1,296
====================================================================================================================================
(1)  Estimated solely for the purpose of calculating the registration fee
      pursuant to Rule 457(h). The fee is calculated on the basis of the average
      of the high and low sale prices of the registrant's Common Stock reported
      on the Nasdaq National Market on December 15, 1998.

================================================================================
2

This Registration Statement on Form S-8 (the "Registration Statement") of FORE
Systems, Inc. (the "Company") relates to the registration of the issuance and
sale of up to an aggregate of 249,238 shares of the Company's Common Stock, par
value $.01 per share ("Common Stock"), pursuant to the Company's 1995 Stock
Incentive Plan (the "Plan"). A registration statement on Form S-8 (File No.
33-99350) (the "November Registration Statement") with respect to the issuance
and sale of up to an aggregate of 5,600,000 shares of Common Stock issuable
under the Plan was filed with the Securities and Exchange Commission (the
"Commission") on November 14, 1995 and is currently effective. A registration
statement on Form S-8 (File No. 333-4052) (the "April Registration Statement")
with respect to the issuance and sale of up to an aggregate of 3,383,700 shares
of Common Stock issuable under the Plan was filed with the Commission on April
24, 1996 and is currently effective. A registration statement on Form S-8 (File
No. 333-47483) (the "March Registration Statement") with respect to the issuance
and sale of up to an aggregate of 968,986 shares of Common Stock issuable under
the Plan was filed with the Commission on March 6, 1998 and is currently
effective. The contents of the November Registration Statement, the April
Registration Statement and the March Registration Statement are hereby
incorporated by reference into this Registration Statement.

                                     PART II

               INFORMATION REQUIRED IN THE REGISTRATION STATEMENT

ITEM 3.   INCORPORATION OF DOCUMENTS BY REFERENCE.

         In addition to the documents incorporated by reference into the
November Registration Statement, the April Registration Statement and the March
Registration Statement, the following documents filed with the Commission are
incorporated by reference into this Registration Statement:

         1. The Company's Annual Report on Form 10-K, filed with the Commission
for the fiscal year ended March 31, 1998 (No. 0-24156);

         2. The Company's Quarterly Report on Form 10-Q, filed with the
Commission for the quarterly period ended June 30, 1998 (No. 0-24156);

         3. The Company's Quarterly Report on Form 10-Q, filed with the
Commission for the quarterly period ended September 30, 1998 (No. 0-24156);

         4. The Company's Current Report on Form 8-K, dated September 11, 1998;

         5. The Company's Current Report on Form 8-K/A Amendment No. 1, dated
September 11, 1998; and

         6. The Company's Current Report on Form 8-K, dated October 1, 1998.

         All documents subsequently filed by the Company with the Commission
pursuant to Sections 13(a), 13(c), 14 and 15(d) of the Exchange Act after the
date of this Registration Statement, but prior to the filing of a post-effective
amendment to this Registration Statement which indicates that all securities
offered by this Registration Statement have been sold or which deregisters all
such securities then remaining unsold, shall be deemed to be incorporated by
reference into this Registration Statement. Each document incorporated by
reference into this Registration Statement shall be deemed to be a part of this
Registration Statement from the date of the filing of such document with the
Commission until the information contained therein is superseded or updated by
any subsequently filed document which is incorporated by reference into this
Registration Statement or by any document which constitutes part of the
prospectus relating to the Plan meeting the requirements of Section 10(a) of the
Securities Act of 1933, as amended (the "Securities Act").

                                      II-1
3

ITEM 5.   INTERESTS OF NAMED EXPERTS AND COUNSEL.

         The validity of the shares of Common Stock to be issued under this
Registration Statement will be passed upon for the Company by Morgan, Lewis &
Bockius LLP, Pittsburgh, Pennsylvania. As of December 22, 1998, Marlee S. Myers,
a partner of Morgan, Lewis & Bockius LLP, held options to acquire up to 40,000
shares of Common Stock.

ITEM 8.   EXHIBITS.

         The following exhibits are filed herewith or incorporated by reference
as part of this Registration Statement:
EXHIBIT NO.                                                 DESCRIPTION
-----------------     --------------------------------------------------------------------------------------------
4.1             Amended and Restated Certificate of Incorporation of FORE Systems, Inc. (as amended by
                      Certificate of Amendment dated May 6, 1996) (incorporated by reference to Exhibit 3.1 to the
                      Company's Annual Report on Form 10-K for the fiscal year ended March 31, 1996).

      4.2             Second Amended and Restated By-Laws of FORE Systems, Inc. (as amended through March 5, 1997)
                      (incorporated by reference to Exhibit 3.2 to the Company's Annual Report on Form 10-K for
                      the fiscal year ended March 31, 1997).

      4.3             FORE Systems, Inc. 1995 Stock Incentive Plan (incorporated by reference to Exhibit 4.3 to
                      the Company's Registration Statement on Form S-8 (File No. 33-99350)).

      5.1             Opinion of Morgan, Lewis & Bockius LLP as to the legality of the shares being registered.

      23.1            Consent of PricewaterhouseCoopers LLP, independent accountants.

      23.2            Consent of Morgan, Lewis & Bockius LLP (included in opinion filed as Exhibit 5.1).

      24.1            Power of Attorney (set forth on the signature page of this Registration Statement).
II-2
4

                                   SIGNATURES

         Pursuant to the requirements of the Securities Act, 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 Borough of Warrendale, Commonwealth of Pennsylvania, on
December 22, 1998.

                                 FORE Systems, Inc.

                                 By: /s/ Thomas J. Gill                      
                                     ----------------------------
                                     Thomas J. Gill
                                     President and Chief Executive Officer

         KNOW ALL MEN BY THESE PRESENTS, that each of the undersigned directors
and officers of FORE Systems, Inc. hereby constitutes and appoints Thomas J.
Gill and Bruce E. Haney, and each of them, his true and lawful attorneys-in-fact
and agents, for him and in his name, place and stead, in any and all capacities,
to sign one or more amendments to this Registration Statement on Form S-8 under
the Securities Act, including post-effective amendments and other related
documents, and to file the same with the Commission under said Act, hereby
granting power and authority to do and perform any and all acts and things
requisite and necessary to be done in and about the premises, as fully as to all
intents and purposes as he might or could do in person, hereby ratifying and
confirming all that said attorneys-in-fact and agents may lawfully do or cause
to be done by virtue hereof.

         Pursuant to the requirements of the Securities Act, this Registration
Statement and the foregoing Power of Attorney have been signed by the following
persons in the capacities and on the date(s) indicated:
Signature                                        Title                                  Date
              ---------                                        -----                                  ----
/s/ Eric C. Cooper                         Chairman and a Director                              December 22, 1998
--------------------------------
Eric C. Cooper

/s/ Thomas J. Gill                         President and Chief Executive Officer                December 22, 1998
--------------------------------           (Principal Executive Officer) and a Director
Thomas J. Gill                             

/s/ Robert D. Sansom                       Senior Vice President and Chief Technical            December 22, 1998
--------------------------------           Officer and a Director
Robert D. Sansom                           

/s/ Bruce E. Haney                         Senior Vice President and Chief Financial            December 22, 1998
--------------------------------           Officer (Principal Financial Officer)
Bruce E. Haney                             

/s/ Gary J. Brunner                        Vice President, Controller and Treasurer             December 22, 1998
--------------------------------           (Principal Accounting Officer)
Gary J. Brunner                            

/s/ John C. Baker                          Director                                             December 22, 1998
--------------------------------
John C. Baker

/s/ Daniel W. McGlaughlin                  Director                                             December 22, 1998
--------------------------------
Daniel W. McGlaughlin

/s/ Daniel R. Hesse                        Director                                             December 22, 1998
--------------------------------
Daniel R. Hesse

/s/ John T. LaMacchia                      Director                                             December 22, 1998
--------------------------------
John T. LaMacchia
5

                                  EXHIBIT INDEX
EXHIBIT NO.                                                 DESCRIPTION
-----------------     --------------------------------------------------------------------------------------------
4.1             Amended and Restated Certificate of Incorporation of FORE Systems, Inc. (as amended by
                      Certificate of Amendment dated May 6, 1996) (incorporated by reference to Exhibit 3.1 to the
                      Company's Annual Report on Form 10-K for the fiscal year ended March 31, 1996).

      4.2             Second Amended and Restated By-Laws of FORE Systems, Inc. (as amended through March 5, 1997)
                      (incorporated by reference to Exhibit 3.2 to the Company's Annual Report on Form 10-K for
                      the fiscal year ended March 31, 1997).

      4.3             FORE Systems, Inc. 1995 Stock Incentive Plan (incorporated by reference to Exhibit 4.3 to
                      the Company's Registration Statement on Form S-8 (File No. 33-99350)).

      5.1             Opinion of Morgan, Lewis & Bockius LLP as to the legality of the shares being registered.

      23.1            Consent of PricewaterhouseCoopers LLP, independent accountants.

      23.2            Consent of Morgan, Lewis & Bockius LLP (included in opinion filed as Exhibit 5.1).

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