<PAGE>

                      SECURITIES AND EXCHANGE COMMISSION
                             Washington, DC  20549

                               ________________

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

                               ________________

                               GSI LUMONICS INC.
            (Exact name of registrant as specified in its charter)

    New Brunswick, Canada                                 38-1859358
  (State or other jurisdiction                 (IRS Employer Identification No.)
of incorporation or organization)

             105 Schneider Road, Kanata, Ontario, Canada  K2K 1Y3
              (Address of principal executive offices) (Zip code)

                                ________________

              1995 Stock Option Plan for Employees and Directors
                          (Full titles of the plans)

                               ________________

                              Charles D. Winston
                                39 Manning Road
                             Billerica, MA  01821
                                (978) 439-5511
                    (Name and address of agent for service)
         (Telephone number, including area code, of agent for service)

                                    Copy to:
        Charles J. Gardner                         Mark L. Weissler
        GSI Lumonics Inc.                Milbank, Tweed, Hadley & McCloy LLP
        105 Schneider Road                    One Chase Manhattan Plaza
 Kanata, Ontario, Canada  K2K 1Y3             New York, New York  10005
          (613) 592-1460                            (212) 530-5000

                                ________________

                        CALCULATION OF REGISTRATION FEE
<TABLE>
<CAPTION>

   Title of Securities To Be      Amount To Be  Proposed Maximum  Proposed Maximum     Amount of
         Registered                Registered    Offering Price      Aggregate      Registration Fee
                                                  Per Share *     Offering Price*
----------------------------------------------------------------------------------------------------
<S>                               <C>           <C>               <C>               <C>
Common Stock, no par value......     2,000,000            $20.41       $40,820,000           $10,777
====================================================================================================
</TABLE>

* Estimated solely for the purpose of calculating the registration fee in
  accordance with Rule 457(h) under the Securities Act of 1933, as amended.
<PAGE>

                                    PART II

              INFORMATION REQUIRED IN THE REGISTRATION STATEMENT

Item 3.  Incorporation of Documents by Reference

         We hereby incorporate by reference in this registration statement the
following documents:

         (1)  our annual report on Form 10-K for the year ended December 31,
              1999;

         (2)  our current report on Form 8-K dated March 9, 2000;

         (3)  our quarterly reports on Form 10-Q dated May 5, 2000 and August 3,
              2000; and

         (4)  the description of our common stock incorporated by reference in
              our registration statement on Form 8-A declared effective by the
              Securities and Exchange Commission April 2, 1999.

         In addition, all documents subsequently filed by us pursuant to
Sections 13(a), 13(c), 14 and 15(d) of the Securities Exchange Act of 1934, as
amended, prior to the filing of a post-effective amendment which indicates that
all securities offered hereby have been sold or which deregisters all of such
securities then remaining unsold shall be deemed to be incorporated by reference
into this registration statement and to be a part hereof from the date of filing
of such documents.

ITEM 4.  DESCRIPTION OF SECURITIES

         Not applicable.

ITEM 5.  INTERESTS OF NAMED EXPERTS OR COUNSEL

         Not applicable.

ITEM 6.  INDEMNIFICATION OF DIRECTORS AND OFFICERS

         Subject to Section 81 of the Business Corporations Act, New Brunswick,
as from time to time amended, except in respect of an action by or on behalf of
the registrant or Another Body Corporate (as defined below) to procure a
judgment in its favor, the registrant must indemnify each director and officer
and each former director and officer and each person who acts or acted at the
registrant's request as a director or officer of Another Body Corporate, and his
heirs and legal representatives, against all costs, charges and expenses,
including any amount paid to settle an action or satisfy a judgment, reasonably
incurred by him in respect of any civil, criminal or administrative action or
proceeding to which he is made a party by reason of being or having been a
director or officer of the Corporation or Another Body Corporate, as the case
may be, if

<PAGE>

         (a)  he acted honestly and in good faith with a view to the best
     interests of the registrant; and

         (b)  in the case of a criminal or administrative action or proceeding
     that is enforced by a monetary penalty, he had reasonable grounds for
     believing that his conduct was lawful.

"Another Body Corporate" as used herein means a body corporate of which the
registrant is or was a shareholder or creditor.

We maintain directors' and officers' liability insurance in the aggregate
principal amount of $35,000,000 subject to a $1,000,000 deductible per loss
payable by us.  The premium payable for such insurance is currently $104,000 per
year which is paid by us.

ITEM 7.  EXEMPTION FROM REGISTRATION CLAIMED

         Not applicable.

ITEM 8.  EXHIBITS

    4.1  1995 Stock Option Plan for Employees and Directors.

    5.1  Opinion of Stewart McKelvey Stirling Scales regarding the legality of
         the shares being registered, including consent.

   23.1  Consent of Stewart McKelvey Stirling Scales (included in Exhibit 5.1).

   23.2  Consent of Ernst & Young LLP, independent public accountants.

   24.1  Power of Attorney (included in signature pages).

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;

         (i)     To include any prospectus required by Section 10(a)(3) of the
                 Securities Act of 1933, as amended;

         (ii)    To reflect in the prospectus any facts or events arising after
                 the effective date of the registration statement (or the most
                 recent post-effective amendment thereof) which, individually or
                 in the aggregate, represent a fundamental change in the
                 information set forth in the registration statement.
                 Notwithstanding the foregoing, any increase or decrease in
                 volume of securities offered (if the total dollar value of
                 securities offered would not exceed that which was registered)
                 and any deviation from the low or high end of the estimated
                 maximum offering range may be reflected in the form of

<PAGE>

                 prospectus filed with the Securities and Exchange Commission
                 pursuant to Rule 424(b) if, in the aggregate, the changes in
                 volume and price represent no more than a 20 percent change in
                 the maximum aggregate offering price set forth in the
                 "Calculation of Registration Fee" table in the effective
                 registration statement; and

         (iii)   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;

     provided, however, that paragraphs (a)(1)(i) and (a)(1)(ii) do not apply if
     the information required to be included in a post-effective amendment by
     those paragraphs is contained in periodic reports filed with or furnished
     to the Securities and Exchange Commission by the registrant pursuant to
     Section 13 or 15(d) of the Securities Exchange Act of 1934, as amended,
     that are incorporated by reference in the registration statement.

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

         (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 of 1933, as
              amended, each filing of the registrant's annual report pursuant to
              Section 13(a) or 15(d) of the Securities Exchange Act of 1934, as
              amended (and, where applicable, each filing of an employee benefit
              plan's annual report pursuant to Section 15(d) of the Securities
              Exchange Act of 1934, as amended), 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 of 1933, as amended, 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 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 Act and will be
              governed by the final adjudication of such issue.

<PAGE>

                                  SIGNATURES

         Pursuant to the requirements of the Securities Act of 1933, 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 City of Ottawa, Province of Ontario, on August 4, 2000.

                              GSI LUMONICS INC.

                              By: /s/ Charles D. Winston
                                  ----------------------
                                  Name:  Charles D. Winston
                                  Title: Chief Executive Officer

                               POWER OF ATTORNEY

         Each person whose signature appears below hereby appoints Desmond J.
Bradley and Charles J. Gardner and each of them severally, acting alone and
without the other, his true and lawful attorney-in-fact with the authority to
execute in the name of each such person, and to file with the Securities and
Exchange Commission, together with any exhibits thereto and other documents
therewith, any and all amendments (including without limitation post-effective
amendments) to this registration statement on Form S-8 necessary or advisable to
enable the registrant to comply with the Securities Act of 1933, as amended, and
any rules, regulations, and requirements of the Securities and Exchange
Commission in respect thereof, which amendments may make such other changes in
the Registration Statement as the aforesaid attorney-in-fact executing the same
deems appropriate.

         Pursuant to the requirements of the Securities Act of 1933 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/ Charles D. Winston          Chief Executive Officer and authorized      August 4, 2000
------------------------------  representative in the United States
Charles D. Winston              (Principal Executive Officer)

/s/ Desmond J. Bradley          Chief Financial Officer                     August 4, 2000
------------------------------  (Principal Financial and Accounting
Desmond J. Bradley              Officer)

/s/ Richard B. Black            Director                                    August 4, 2000
------------------------------
Richard B. Black

/s/ Paul F. Ferrari             Director                                    August 4, 2000
------------------------------
Paul F. Ferrari

</TABLE>
<PAGE>
<TABLE>
<CAPTION>
<S>                            <C>                                        <C>
/s/ Byron O. Pond               Director                                    August 4, 2000
------------------------------
Byron O. Pond

/s/ Benjamin J. Virgilio        Director                                    August 4, 2000
------------------------------
Benjamin J. Virgilio

                                Director
------------------------------
Woodie C. Floowers

                                Director
------------------------------
William B. Waite
</TABLE>

<PAGE>

                                 EXHIBIT INDEX

EXHIBIT NO    DESCRIPTION

     4.1      1995 Stock Option Plan for Employees and Directors.

     5.1      Opinion of Stewart McKelvey Stirling Scales regarding the legality
              of the shares being registered, including consent.

    23.1      Consent of Stewart McKelvey Stirling Scales (included in Exhibit
              5.1).

    23.2      Consent of Ernst & Young LLP, independent public accountants.

    24.1      Power of Attorney (included in signature pages).
[{"type": "S-8", "sequence": "1", "filename": "0001.txt", "description": "FORM S-8", "secsgml_size_bytes": 15376}]
{"company-data": {"conformed-name": "GSI LUMONICS INC", "cik": "0001076930", "assigned-sic": "3559", "irs-number": "381859358", "state-of-incorporation": "A3", "fiscal-year-end": "1231"}, "filing-values": {"form-type": "S-8", "act": "33", "file-number": "333-43080", "film-number": "686490"}, "business-address": {"street1": "105 SCHNEIDER RD KANATA", "street2": "ONTARIO CANADA", "city": "K2K 1Y3"}, "mail-address": {"street1": "105 SCHNEIDER RD KANATA", "street2": "ONTARIO CANADA", "city": "K2K 1Y3"}, "former-company": [{"former-conformed-name": "GSI LUMONICS", "date-changed": "19990331"}, {"former-conformed-name": "LUMONICS INC", "date-changed": "19990115"}]}
SECURITIES AND EXCHANGE COMMISSION
                             Washington, DC  20549

                               ________________

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

                               ________________

                               GSI LUMONICS INC.
            (Exact name of registrant as specified in its charter)

    New Brunswick, Canada                                 38-1859358
  (State or other jurisdiction                 (IRS Employer Identification No.)
of incorporation or organization)

             105 Schneider Road, Kanata, Ontario, Canada  K2K 1Y3
              (Address of principal executive offices) (Zip code)

                                ________________

              1995 Stock Option Plan for Employees and Directors
                          (Full titles of the plans)

                               ________________

                              Charles D. Winston
                                39 Manning Road
                             Billerica, MA  01821
                                (978) 439-5511
                    (Name and address of agent for service)
         (Telephone number, including area code, of agent for service)

                                    Copy to:
        Charles J. Gardner                         Mark L. Weissler
        GSI Lumonics Inc.                Milbank, Tweed, Hadley & McCloy LLP
        105 Schneider Road                    One Chase Manhattan Plaza
 Kanata, Ontario, Canada  K2K 1Y3             New York, New York  10005
          (613) 592-1460                            (212) 530-5000

                                ________________

                        CALCULATION OF REGISTRATION FEE
Title of Securities To Be      Amount To Be  Proposed Maximum  Proposed Maximum     Amount of
         Registered                Registered    Offering Price      Aggregate      Registration Fee
                                                  Per Share *     Offering Price*
----------------------------------------------------------------------------------------------------
Common Stock, no par value......     2,000,000            $20.41       $40,820,000           $10,777
====================================================================================================
* Estimated solely for the purpose of calculating the registration fee in
  accordance with Rule 457(h) under the Securities Act of 1933, as amended.
PART II

              INFORMATION REQUIRED IN THE REGISTRATION STATEMENT

Item 3.  Incorporation of Documents by Reference

         We hereby incorporate by reference in this registration statement the
following documents:

         (1)  our annual report on Form 10-K for the year ended December 31,
              1999;

         (2)  our current report on Form 8-K dated March 9, 2000;

         (3)  our quarterly reports on Form 10-Q dated May 5, 2000 and August 3,
              2000; and

         (4)  the description of our common stock incorporated by reference in
              our registration statement on Form 8-A declared effective by the
              Securities and Exchange Commission April 2, 1999.

         In addition, all documents subsequently filed by us pursuant to
Sections 13(a), 13(c), 14 and 15(d) of the Securities Exchange Act of 1934, as
amended, prior to the filing of a post-effective amendment which indicates that
all securities offered hereby have been sold or which deregisters all of such
securities then remaining unsold shall be deemed to be incorporated by reference
into this registration statement and to be a part hereof from the date of filing
of such documents.

ITEM 4.  DESCRIPTION OF SECURITIES

         Not applicable.

ITEM 5.  INTERESTS OF NAMED EXPERTS OR COUNSEL

         Not applicable.

ITEM 6.  INDEMNIFICATION OF DIRECTORS AND OFFICERS

         Subject to Section 81 of the Business Corporations Act, New Brunswick,
as from time to time amended, except in respect of an action by or on behalf of
the registrant or Another Body Corporate (as defined below) to procure a
judgment in its favor, the registrant must indemnify each director and officer
and each former director and officer and each person who acts or acted at the
registrant's request as a director or officer of Another Body Corporate, and his
heirs and legal representatives, against all costs, charges and expenses,
including any amount paid to settle an action or satisfy a judgment, reasonably
incurred by him in respect of any civil, criminal or administrative action or
proceeding to which he is made a party by reason of being or having been a
director or officer of the Corporation or Another Body Corporate, as the case
may be, if
(a)  he acted honestly and in good faith with a view to the best
     interests of the registrant; and

         (b)  in the case of a criminal or administrative action or proceeding
     that is enforced by a monetary penalty, he had reasonable grounds for
     believing that his conduct was lawful.

"Another Body Corporate" as used herein means a body corporate of which the
registrant is or was a shareholder or creditor.

We maintain directors' and officers' liability insurance in the aggregate
principal amount of $35,000,000 subject to a $1,000,000 deductible per loss
payable by us.  The premium payable for such insurance is currently $104,000 per
year which is paid by us.

ITEM 7.  EXEMPTION FROM REGISTRATION CLAIMED

         Not applicable.

ITEM 8.  EXHIBITS

    4.1  1995 Stock Option Plan for Employees and Directors.

    5.1  Opinion of Stewart McKelvey Stirling Scales regarding the legality of
         the shares being registered, including consent.

   23.1  Consent of Stewart McKelvey Stirling Scales (included in Exhibit 5.1).

   23.2  Consent of Ernst & Young LLP, independent public accountants.

   24.1  Power of Attorney (included in signature pages).

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;

         (i)     To include any prospectus required by Section 10(a)(3) of the
                 Securities Act of 1933, as amended;

         (ii)    To reflect in the prospectus any facts or events arising after
                 the effective date of the registration statement (or the most
                 recent post-effective amendment thereof) which, individually or
                 in the aggregate, represent a fundamental change in the
                 information set forth in the registration statement.
                 Notwithstanding the foregoing, any increase or decrease in
                 volume of securities offered (if the total dollar value of
                 securities offered would not exceed that which was registered)
                 and any deviation from the low or high end of the estimated
                 maximum offering range may be reflected in the form of
prospectus filed with the Securities and Exchange Commission
                 pursuant to Rule 424(b) if, in the aggregate, the changes in
                 volume and price represent no more than a 20 percent change in
                 the maximum aggregate offering price set forth in the
                 "Calculation of Registration Fee" table in the effective
                 registration statement; and

         (iii)   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;

     provided, however, that paragraphs (a)(1)(i) and (a)(1)(ii) do not apply if
     the information required to be included in a post-effective amendment by
     those paragraphs is contained in periodic reports filed with or furnished
     to the Securities and Exchange Commission by the registrant pursuant to
     Section 13 or 15(d) of the Securities Exchange Act of 1934, as amended,
     that are incorporated by reference in the registration statement.

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

         (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 of 1933, as
              amended, each filing of the registrant's annual report pursuant to
              Section 13(a) or 15(d) of the Securities Exchange Act of 1934, as
              amended (and, where applicable, each filing of an employee benefit
              plan's annual report pursuant to Section 15(d) of the Securities
              Exchange Act of 1934, as amended), 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 of 1933, as amended, 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 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 Act and will be
              governed by the final adjudication of such issue.
SIGNATURES

         Pursuant to the requirements of the Securities Act of 1933, 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 City of Ottawa, Province of Ontario, on August 4, 2000.

                              GSI LUMONICS INC.

                              By: /s/ Charles D. Winston
                                  ----------------------
                                  Name:  Charles D. Winston
                                  Title: Chief Executive Officer

                               POWER OF ATTORNEY

         Each person whose signature appears below hereby appoints Desmond J.
Bradley and Charles J. Gardner and each of them severally, acting alone and
without the other, his true and lawful attorney-in-fact with the authority to
execute in the name of each such person, and to file with the Securities and
Exchange Commission, together with any exhibits thereto and other documents
therewith, any and all amendments (including without limitation post-effective
amendments) to this registration statement on Form S-8 necessary or advisable to
enable the registrant to comply with the Securities Act of 1933, as amended, and
any rules, regulations, and requirements of the Securities and Exchange
Commission in respect thereof, which amendments may make such other changes in
the Registration Statement as the aforesaid attorney-in-fact executing the same
deems appropriate.

         Pursuant to the requirements of the Securities Act of 1933 this
registration statement has been signed by the following persons in the
capacities and on the dates indicated.
Signature                               Title                             Date
------------------------------  ------------------------------------------  --------------------
/s/ Charles D. Winston          Chief Executive Officer and authorized      August 4, 2000
------------------------------  representative in the United States
Charles D. Winston              (Principal Executive Officer)

/s/ Desmond J. Bradley          Chief Financial Officer                     August 4, 2000
------------------------------  (Principal Financial and Accounting
Desmond J. Bradley              Officer)

/s/ Richard B. Black            Director                                    August 4, 2000
------------------------------
Richard B. Black

/s/ Paul F. Ferrari             Director                                    August 4, 2000
------------------------------
Paul F. Ferrari
/s/ Byron O. Pond               Director                                    August 4, 2000
------------------------------
Byron O. Pond

/s/ Benjamin J. Virgilio        Director                                    August 4, 2000
------------------------------
Benjamin J. Virgilio

                                Director
------------------------------
Woodie C. Floowers

                                Director
------------------------------
William B. Waite
EXHIBIT INDEX

EXHIBIT NO    DESCRIPTION

     4.1      1995 Stock Option Plan for Employees and Directors.

     5.1      Opinion of Stewart McKelvey Stirling Scales regarding the legality
              of the shares being registered, including consent.

    23.1      Consent of Stewart McKelvey Stirling Scales (included in Exhibit
              5.1).

    23.2      Consent of Ernst & Young LLP, independent public accountants.

    24.1      Power of Attorney (included in signature pages).