<PAGE>

        As filed with the Securities and Exchange Commission on October 15, 1999
                                                  Registration No. 33-__________

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

                      SECURITIES AND EXCHANGE COMMISSION
                            Washington, D.C. 20549
                            ----------------------

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

                                 XIRCOM, INC.
              (Exact name of issuer as specified in its charter)

--------------------------------------------------------------------------------
         California                                        95-4221884

    (State of Incorporation)                   (IRS Employer Identification No.)

                          2300 Corporate Center Drive
                        Thousand Oaks, California 91320
                   (Address of Principal Executive Offices)
                             ____________________
           ENTREGA TECHNOLOGIES, INC. STOCK OPTION PLAN, AS AMENDED
                           (Full title of the plan)
                             ____________________
                              Steven F. DeGennaro
                            Chief Financial Officer
                                 XIRCOM, INC.
                          2300 Corporate Center Drive
                        Thousand Oaks, California 91320
                    (Name and address of agent for service)
                                (805) 376-9300
         (Telephone number, including area code, of agent for service)
                             ____________________
                                   Copy to:
                            Howard S. Zeprun, Esq.
                       WILSON SONSINI GOODRICH & ROSATI
                           Professional Corporation
                              650 Page Mill Road
                          Palo Alto, California 94304
                           Telephone: (415) 493-9300

                        CALCULATION OF REGISTRATION FEE

<TABLE>
<CAPTION>
============================================================================================================
Title of Securities    Amount to         Proposed Maximum             Proposed Maximum         Amount of
to be Registered     be Registered    Offering Price Per Share    Aggregate Offering Price  Registration Fee
============================================================================================================
<S>                  <C>              <C>                         <C>                       <C>
Common Stock,
$0.001 par value
  Upon exercise of
  options under
  Entrega                76,914 shs.           $5.83(1)                  $448,408.62             $124.66
Technologies, Inc.
Stock Option Plan,
as amended

TOTAL.............                                                                               $124.66
</TABLE>

___________________________
(1) Such shares are issuable upon exercise of outstanding options with fixed
exercise prices.  Pursuant to rule 457(h), the aggregate offering price and the
fee have been computed upon the basis of the price at which the options may be
exercised.  The offering price per share set forth for such shares is the
exercise price per share at which such options are exercisable.

================================================================================
<PAGE>

                                 XIRCOM, INC.
                      REGISTRATION STATEMENT ON FORM S-8

                                    PART II

                INFORMATION REQUIRED IN REGISTRATION STATEMENT


Item 3.   Incorporation of Documents by Reference.
          ---------------------------------------

     There are hereby incorporated by reference in this Registration Statement
the following documents and information heretofore filed with the Securities and
Exchange Commission:

     1.   The Company's Annual Report on Form 10-K for the year ended September
30, 1998, filed pursuant to Section 13 of the Securities Exchange Act of 1934,
as amended (the "Exchange Act").

     2.   The Company's Quarterly Reports on Form 10-Q for the quarters ending
December 31, 1998, March 31, 1999 and June 30, 1999 filed pursuant to Section 13
of the Exchange Act.

     3.   The Company's Current Report on Form 8-K filed with the SEC dated
February 18, 1999, filed pursuant to Section 13 of the Exchange Act.

     4.   The description of the Company's Common Stock contained in the
Company's Registration Statement on Form 8-A dated February 11, 1992, filed
pursuant to Section 12 of the Exchange Act, including any amendment or report
filed for the purpose of updating such description.

     All documents filed by the Company pursuant to Sections 13(a), 13(c), 14
and 15(d) of the Exchange Act on or after the date of this Registration
Statement and 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 in this
Registration Statement and to be part hereof from the date of filing of such
documents.

Item 6.   Indemnification of Directors and Officers.
          -----------------------------------------

     Section 204 of the General Corporation Law of the State of California
("California Law") authorizes a corporation to adopt a provision in its articles
of incorporation eliminating the personal liability of directors to corporations
and their shareholders for monetary damages for breach or alleged breach of
directors' "duty of care."  Following a California corporation's adoption of
such a provision, its directors are not accountable to corporations and their
shareholders for monetary damages for conduct constituting negligence (or gross
negligence) in the exercise of their fiduciary duties; however, directors
continue to be subject to equitable

                                      II-1
<PAGE>

remedies such as injunction or rescission. Under California Law, a director also
continues to be liable for (1) a breach of his or her duty of loyalty; (2) acts
or omissions not in good faith or involving intentional misconduct or knowing
violations of law; (3) illegal payments of dividends; and (4) approval of any
transaction from which a director derives an improper personal benefit. The
adoption of such a provision in the articles of incorporation also does not
limit directors' liability for violations of the federal securities laws.

     Section 317 of the California Law makes a provision for the indemnification
of officers, directors and other corporate agents in terms sufficiently broad to
indemnify such persons, under certain circumstances, for liabilities (including
reimbursement for expenses incurred) arising under the Securities Act of 1933,
as amended (the "Securities Act").  An amendment to Section 317 provides that
the indemnification provided by this section is not exclusive to the extent
additional rights are authorized in a corporation's articles of incorporation.

     The Company has adopted provisions in its Amended Articles of Incorporation
which eliminate the liability of its directors for monetary damages and
authorize the Company to indemnify its officers, directors and other agents to
the fullest extent permitted by law.

Item 8.   Exhibits.
          --------

     Exhibit
     Number         Description
     -------        -----------

     4.1       Entrega Technologies, Inc. Stock Option Plan, as amended

     23.1      Consent of Ernst & Young LLP, Independent Auditors.

     25.1      Power of Attorney (included in signature pages to 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 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.

          (2)  That, for the purpose of determining any liability under the
Securities Act of 1933, as amended (the "Securities Act") each such post-
effective amendment shall be deemed

                                      II-2
<PAGE>

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, each filing of the
registrant's annual report pursuant to Section 13(a) or Section 15(d) of the
Exchange Act (and, where applicable, each filing of an employee benefit plan's
annual report pursuant to Section 15(d) of the Exchange Act) 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 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 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 whether such
indemnification by it is against public policy as expressed in the Securities
Act and will be governed by the final adjudication of such issue.

                                      II-3
<PAGE>

                                  SIGNATURES

     Pursuant to the requirements of the Securities Act that 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 Thousand Oaks, State of California, on October 12,
1999.

                                   XIRCOM, INC.

                                   By:  /s/ DIRK I. GATES
                                        ------------------------------
                                        Dirk I. Gates, Chairman, President and
                                        Chief Executive Officer

                               POWER OF ATTORNEY

     KNOW ALL PERSONS BY THESE PRESENTS, that each person whose signature
appears below constitutes and appoints Dirk I. Gates and Steven F. DeGennaro,
jointly and severally, his attorneys-in-fact, each with the power of
substitution, for him in any and all capacities, to sign any amendments to this
Registration Statement on Form S-8 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 each of said attorneys-in-
fact, or his substitution or substitutes, may do or cause to be done by virtue
hereof.

     Pursuant to the requirements of the Securities Act, this Registration
Statement has been signed by the following persons in the capacities and on the
dates indicated.

<TABLE>
<CAPTION>
       Signature                               Title                            Date
<S>                            <C>                                         <C>
/s/ DIRK I. GATES              President and Chief Executive Officer       October 12, 1999
----------------------------
(Dirk I. Gates)                and
                               Director (Principal Executive Officer)


/s/ STEVEN F. DEGENNARO        Vice President, Finance and Chief           October 12, 1999
----------------------------
(Steven F. DeGennaro)          Financial Officer
                               (Principal Accounting Officer)

/s/ MICHAEL F. G. ASHBY        Director                                    October 12, 1999
----------------------------
(Michael F. G. Ashby)

/s/ KENNETH J. BIBA            Director                                    October 12, 1999
----------------------------
(Kenneth J. Biba)

/s/ GARY J. BOWEN              Director                                    October 12, 1999
----------------------------
(Gary J. Bowen)

/s/ J. KIRK MATHEWS            Director                                    October 12, 1999
----------------------------
(J. Kirk Mathews)

/s/ CARL E. RUSSO              Director                                    October 12, 1999
----------------------------
(Carl E. Russo)
</TABLE>

                                     II-4
<PAGE>

<TABLE>
<S>                            <C>                                         <C>
/s/ WILLIAM J. SCHROEDER       Director                                    October 12, 1999
----------------------------
(William J. Schroeder)

/s/ DELBERT W. YOCAM           Director                                    October 12, 1999
----------------------------
(Delbert W. Yocam)
</TABLE>

                                     II-5

<PAGE>

                      SECURITIES AND EXCHANGE COMMISSION

                            Washington, D.C. 20549

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

                                   EXHIBITS

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


                      Registration Statement on Form S-8

                                 XIRCOM, INC.

                                     II-6
<PAGE>

                               INDEX TO EXHIBITS

<TABLE>
<CAPTION>
                                                                      Sequentially
  Exhibit                                                               Numbered
  Number                        Description                               Page
  <S>       <C>                                                       <C>
   4.1      Entrega Technologies, Inc. Stock Option Plan, as amended

  23.1      Consent of Ernst & Young LLP, Independent Auditors

  25.1(1)   Power of Attorney (SEE II-5)
</TABLE>



_______________________
EXHIBIT 4.     See page II-4
----------
[{"type": "S-8", "sequence": "1", "description": "FORM S-8", "secsgml_size_bytes": 15428}]
{"company-data": {"conformed-name": "XIRCOM INC", "cik": "0000883905", "assigned-sic": "3576", "irs-number": "954221884", "state-of-incorporation": "CA", "fiscal-year-end": "0930"}, "filing-values": {"form-type": "S-8", "act": "33", "file-number": "333-89099", "film-number": "99728945"}, "business-address": {"street1": "2300 CORPORATE CENTER DR", "city": "THOUSAND OAKS", "state": "CA", "zip": "91320-1420", "phone": "8053769300"}, "mail-address": {"street1": "2300 CORPORATE CENTER DRIVE", "city": "THOUSAND OAKS", "state": "CA", "zip": "91320-1420"}}
As filed with the Securities and Exchange Commission on October 15, 1999
                                                  Registration No. 33-__________

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

                      SECURITIES AND EXCHANGE COMMISSION
                            Washington, D.C. 20549
                            ----------------------

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

                                 XIRCOM, INC.
              (Exact name of issuer as specified in its charter)

--------------------------------------------------------------------------------
         California                                        95-4221884

    (State of Incorporation)                   (IRS Employer Identification No.)

                          2300 Corporate Center Drive
                        Thousand Oaks, California 91320
                   (Address of Principal Executive Offices)
                             ____________________
           ENTREGA TECHNOLOGIES, INC. STOCK OPTION PLAN, AS AMENDED
                           (Full title of the plan)
                             ____________________
                              Steven F. DeGennaro
                            Chief Financial Officer
                                 XIRCOM, INC.
                          2300 Corporate Center Drive
                        Thousand Oaks, California 91320
                    (Name and address of agent for service)
                                (805) 376-9300
         (Telephone number, including area code, of agent for service)
                             ____________________
                                   Copy to:
                            Howard S. Zeprun, Esq.
                       WILSON SONSINI GOODRICH & ROSATI
                           Professional Corporation
                              650 Page Mill Road
                          Palo Alto, California 94304
                           Telephone: (415) 493-9300

                        CALCULATION OF REGISTRATION FEE
============================================================================================================
Title of Securities    Amount to         Proposed Maximum             Proposed Maximum         Amount of
to be Registered     be Registered    Offering Price Per Share    Aggregate Offering Price  Registration Fee
============================================================================================================
Common Stock,
$0.001 par value
  Upon exercise of
  options under
  Entrega                76,914 shs.           $5.83(1)                  $448,408.62             $124.66
Technologies, Inc.
Stock Option Plan,
as amended

TOTAL.............                                                                               $124.66
___________________________
(1) Such shares are issuable upon exercise of outstanding options with fixed
exercise prices.  Pursuant to rule 457(h), the aggregate offering price and the
fee have been computed upon the basis of the price at which the options may be
exercised.  The offering price per share set forth for such shares is the
exercise price per share at which such options are exercisable.

================================================================================
XIRCOM, INC.
                      REGISTRATION STATEMENT ON FORM S-8

                                    PART II

                INFORMATION REQUIRED IN REGISTRATION STATEMENT

Item 3.   Incorporation of Documents by Reference.
          ---------------------------------------

     There are hereby incorporated by reference in this Registration Statement
the following documents and information heretofore filed with the Securities and
Exchange Commission:

     1.   The Company's Annual Report on Form 10-K for the year ended September
30, 1998, filed pursuant to Section 13 of the Securities Exchange Act of 1934,
as amended (the "Exchange Act").

     2.   The Company's Quarterly Reports on Form 10-Q for the quarters ending
December 31, 1998, March 31, 1999 and June 30, 1999 filed pursuant to Section 13
of the Exchange Act.

     3.   The Company's Current Report on Form 8-K filed with the SEC dated
February 18, 1999, filed pursuant to Section 13 of the Exchange Act.

     4.   The description of the Company's Common Stock contained in the
Company's Registration Statement on Form 8-A dated February 11, 1992, filed
pursuant to Section 12 of the Exchange Act, including any amendment or report
filed for the purpose of updating such description.

     All documents filed by the Company pursuant to Sections 13(a), 13(c), 14
and 15(d) of the Exchange Act on or after the date of this Registration
Statement and 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 in this
Registration Statement and to be part hereof from the date of filing of such
documents.

Item 6.   Indemnification of Directors and Officers.
          -----------------------------------------

     Section 204 of the General Corporation Law of the State of California
("California Law") authorizes a corporation to adopt a provision in its articles
of incorporation eliminating the personal liability of directors to corporations
and their shareholders for monetary damages for breach or alleged breach of
directors' "duty of care."  Following a California corporation's adoption of
such a provision, its directors are not accountable to corporations and their
shareholders for monetary damages for conduct constituting negligence (or gross
negligence) in the exercise of their fiduciary duties; however, directors
continue to be subject to equitable

                                      II-1
remedies such as injunction or rescission. Under California Law, a director also
continues to be liable for (1) a breach of his or her duty of loyalty; (2) acts
or omissions not in good faith or involving intentional misconduct or knowing
violations of law; (3) illegal payments of dividends; and (4) approval of any
transaction from which a director derives an improper personal benefit. The
adoption of such a provision in the articles of incorporation also does not
limit directors' liability for violations of the federal securities laws.

     Section 317 of the California Law makes a provision for the indemnification
of officers, directors and other corporate agents in terms sufficiently broad to
indemnify such persons, under certain circumstances, for liabilities (including
reimbursement for expenses incurred) arising under the Securities Act of 1933,
as amended (the "Securities Act").  An amendment to Section 317 provides that
the indemnification provided by this section is not exclusive to the extent
additional rights are authorized in a corporation's articles of incorporation.

     The Company has adopted provisions in its Amended Articles of Incorporation
which eliminate the liability of its directors for monetary damages and
authorize the Company to indemnify its officers, directors and other agents to
the fullest extent permitted by law.

Item 8.   Exhibits.
          --------

     Exhibit
     Number         Description
     -------        -----------

     4.1       Entrega Technologies, Inc. Stock Option Plan, as amended

     23.1      Consent of Ernst & Young LLP, Independent Auditors.

     25.1      Power of Attorney (included in signature pages to 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 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.

          (2)  That, for the purpose of determining any liability under the
Securities Act of 1933, as amended (the "Securities Act") each such post-
effective amendment shall be deemed

                                      II-2
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, each filing of the
registrant's annual report pursuant to Section 13(a) or Section 15(d) of the
Exchange Act (and, where applicable, each filing of an employee benefit plan's
annual report pursuant to Section 15(d) of the Exchange Act) 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 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 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 whether such
indemnification by it is against public policy as expressed in the Securities
Act and will be governed by the final adjudication of such issue.

                                      II-3
SIGNATURES

     Pursuant to the requirements of the Securities Act that 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 Thousand Oaks, State of California, on October 12,
1999.

                                   XIRCOM, INC.

                                   By:  /s/ DIRK I. GATES
                                        ------------------------------
                                        Dirk I. Gates, Chairman, President and
                                        Chief Executive Officer

                               POWER OF ATTORNEY

     KNOW ALL PERSONS BY THESE PRESENTS, that each person whose signature
appears below constitutes and appoints Dirk I. Gates and Steven F. DeGennaro,
jointly and severally, his attorneys-in-fact, each with the power of
substitution, for him in any and all capacities, to sign any amendments to this
Registration Statement on Form S-8 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 each of said attorneys-in-
fact, or his substitution or substitutes, may do or cause to be done by virtue
hereof.

     Pursuant to the requirements of the Securities Act, this Registration
Statement has been signed by the following persons in the capacities and on the
dates indicated.
Signature                               Title                            Date
/s/ DIRK I. GATES              President and Chief Executive Officer       October 12, 1999
----------------------------
(Dirk I. Gates)                and
                               Director (Principal Executive Officer)

/s/ STEVEN F. DEGENNARO        Vice President, Finance and Chief           October 12, 1999
----------------------------
(Steven F. DeGennaro)          Financial Officer
                               (Principal Accounting Officer)

/s/ MICHAEL F. G. ASHBY        Director                                    October 12, 1999
----------------------------
(Michael F. G. Ashby)

/s/ KENNETH J. BIBA            Director                                    October 12, 1999
----------------------------
(Kenneth J. Biba)

/s/ GARY J. BOWEN              Director                                    October 12, 1999
----------------------------
(Gary J. Bowen)

/s/ J. KIRK MATHEWS            Director                                    October 12, 1999
----------------------------
(J. Kirk Mathews)

/s/ CARL E. RUSSO              Director                                    October 12, 1999
----------------------------
(Carl E. Russo)
II-4
/s/ WILLIAM J. SCHROEDER       Director                                    October 12, 1999
----------------------------
(William J. Schroeder)

/s/ DELBERT W. YOCAM           Director                                    October 12, 1999
----------------------------
(Delbert W. Yocam)
II-5
SECURITIES AND EXCHANGE COMMISSION

                            Washington, D.C. 20549

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

                                   EXHIBITS

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

                      Registration Statement on Form S-8

                                 XIRCOM, INC.

                                     II-6
INDEX TO EXHIBITS
Sequentially
  Exhibit                                                               Numbered
  Number                        Description                               Page
4.1      Entrega Technologies, Inc. Stock Option Plan, as amended

  23.1      Consent of Ernst & Young LLP, Independent Auditors

  25.1(1)   Power of Attorney (SEE II-5)
_______________________
EXHIBIT 4.     See page II-4
----------