<PAGE>

   As filed with the Securities and Exchange Commission on January 22, 2002
                                                        Registration No.333-____

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

                      SECURITIES AND EXCHANGE COMMISSION
                            WASHINGTON, D.C.  20549

                                   FORM S-8

                         REGISTRATION STATEMENT UNDER
                          THE SECURITIES ACT OF 1933

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

        Delaware                                         02-0372301
  (State or Other Jurisdiction of           (I.R.S. Employer Identification No.)
  Incorporation or Organization)

                                MatrixOne, Inc.
                               210 Littleton Road
                               Westford, MA 01886
              (Address of Principal Executive Offices) (Zip Code)
                              ____________________

                          1999 Stock Plan, as amended
                            (Full Title of the Plan)

                              ____________________

                               Mark F. O'Connell
                      President & Chief Executive Officer
                                MatrixOne, Inc.
                               210 Littleton Road
                               Westford, MA 01886
                    (Name and Address of Agent For Service)

                                 (978) 589-4000
         (Telephone Number, Including Area Code, of Agent For Service)

                         _____________________________

                                    Copy to:

                           Gordon H. Hayes, Jr., Esq.
                        TESTA, HURWITZ & THIBEAULT, LLP
                                125 High Street
                          Boston, Massachusetts 02110
                                 (617) 248-7000


                        CALCULATION OF REGISTRATION FEE

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

<TABLE>
<CAPTION>
                                                                         Proposed         Proposed
                                                                         Maximum           Maximum
                                                Amount to be          Offering Price      Aggregate            Amount of
Title of Securities to be Registered             Registered             Per Share      Offering Price      Registration Fee (3)
------------------------------------             ----------             ---------      --------------      --------------------
<S>                                             <C>                   <C>              <C>                 <C>
1999 Stock Plan, as amended
Common Stock (Par Value $.01 Per Share)              43,213              $11.70(1)     $    505,592.10            $    46.51
                                                     19,500              $11.50(1)     $    224,250.00            $    20.63
                                                    120,000              $12.86(1)     $  1,543,200.00            $   141.97
                                                     50,000              $14.39(1)     $    719,500.00            $    66.19
                                                  2,767,287              $14.625(2)    $ 40,471,572.38            $ 3,723.38
                                                  ---------              ---------     ---------------            ----------
TOTAL:                                            3,000,000                            $ 43,464,114.48            $ 3,998.70
</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.

(2)  The price of $14.625 per share, which is the average of the high and low
     prices of the Common Stock of the Registrant reported on the Nasdaq
     National Market on January 17, 2002, is set forth solely for purposes of
     calculating the filing fee pursuant to Rule 457(c) and has been used for
     those shares without a fixed exercise price.

(3)  Calculated pursuant to Section 6(b) of the Securities Act of 1933.

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

<PAGE>

     This Registration Statement registers additional securities of the same
class as other securities for which registration statements filed on Form S-8,
SEC File Nos. 333-66458 and 333-35310, of the Registrant are effective. Pursuant
to General Instruction E, the Registrant incorporates the information contained
in the Registrant's Registration Statements on Form S-8 (SEC File Nos. 333-66458
and 333-35310).


                                    PART II

               INFORMATION REQUIRED IN THE REGISTRATION STATEMENT

Item 8.  Exhibits.

Exhibit No.    Description of Exhibit
-----------    ----------------------

4.1            Specimen certificate for shares of the Registrant's common stock,
               $.01 par value per share (filed as Exhibit 4.1 to the
               Registration Statement on Form S-1 (SEC File No. 333-92731) and
               incorporated herein by reference).

4.2            Amended and Restated Certificate of Incorporation (filed as
               Exhibit 3.1 to the Annual Report on Form 10-K for the year ended
               July 1, 2000 and filed on September 22, 2000 (SEC File No. 000-
               29309) and incorporated herein by reference).

4.3            Amended and Restated By-Laws (filed as Exhibit 3.2 to the Annual
               Report on Form 10-K for the year ended July 1, 2000 and filed on
               September 22, 2000 (SEC File No. 000-29309) and incorporated
               herein by reference).

4.4            1999 Stock Plan (filed as Exhibit 4.4 to the Registration
               Statement on Form S-8 (SEC File No. 333-35310) and incorporated
               herein by reference).

4.5            Amendment No. 1 to the 1999 Stock Plan (filed as Exhibit 4.5 to
               the Registration Statement on Form S-8 (SEC File No. 333-66458)
               and incorporated herein by reference).

4.6            Amendment No. 2 to the 1999 Stock Plan, as amended.

4.7            Amendment No. 3 to the 1999 Stock Plan, as amended.

5.1            Opinion of Testa, Hurwitz & Thibeault, LLP.

23.1           Consent of Arthur Andersen LLP.

23.2           Consent of Testa, Hurwitz & Thibeault, LLP (included in Exhibit
               5.1).

24.1           Power of Attorney (included as part of the signature page to this
               Registration Statement).

                                       2
<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 Town of Westford, Commonwealth of Massachusetts, on this
22nd day of January, 2002.

                                      MATRIXONE, INC.

                                      By:  /s/ Mark F. O'Connell
                                         -----------------------
                                           Mark F. O'Connell
                                           President and Chief Executive Officer


                        POWER OF ATTORNEY AND SIGNATURES

     The undersigned officers and directors of MatrixOne, Inc., hereby
constitute and appoint Mark F. O'Connell and Maurice L. Castonguay, and each of
them singly, our true and lawful attorneys-in-fact, with full power to them and
each of them singly, to sign for us in our names in the capacities indicated
below, any amendments to this Registration Statement on Form S-8 (including
post-effective amendments), and to file the same, with all exhibits thereto
and other documents in connection therewith, with the Securities and Exchange
Commission, and generally to do all things in our names and on our behalf in
our capacities as officers and directors to enable MatrixOne, Inc., to comply
with the provisions of the Securities Act of 1933, as amended, hereby ratifying
and confirming our signatures as they may be signed by our said attorneys, or
any of them, to said Registration Statement and all amendments thereto.

     Pursuant to the requirements of the Securities Act of 1933, this
Registration Statement has been signed below by the following persons in the
capacities and on the dates indicated.

<TABLE>
<CAPTION>
     Signature                         Title(s)                                         Date
     ---------                         --------                                         ----
<S>                                    <C>                                              <C>
/s/ Mark F. O'Connell                  President, Chief Executive Officer               January 22, 2002
-----------------------------          and Director (Principal Executive Officer)
Mark F. O'Connell

/s/ Maurice L. Castonguay              Chief Financial Officer, Senior Vice             January 22, 2002
-----------------------------          President of Finance and Administration
Maurice L. Castonguay                  and Treasurer (Principal Financial and
                                       Accounting Officer)


/s/ W. Patrick Decker                  Director                                         January 22, 2002
-----------------------------
W. Patrick Decker

/s/ Daniel J. Holland                  Director                                         January 22, 2002
-----------------------------
Daniel J. Holland

/s/ James F. Morgan                    Director                                         January 22, 2002
-----------------------------
James F. Morgan

/s/ Charles R. Stuckey, Jr.            Director                                         January 22, 2002
-----------------------------
Charles R. Stuckey, Jr.
</TABLE>

                                       3
<PAGE>

                                 EXHIBIT INDEX

Exhibit No.    Description of Exhibit
-----------    ----------------------

4.1            Specimen certificate for shares of the Registrant's common stock,
               $.01 par value per share (filed as Exhibit 4.1 to the
               Registration Statement on Form S-1 (SEC File No. 333-92731) and
               incorporated herein by reference).

4.2            Amended and Restated Certificate of Incorporation (filed as
               Exhibit 3.1 to the Annual Report on Form 10-K for the year ended
               July 1, 2000 and filed on September 22, 2000 (SEC File No. 000-
               29309) and incorporated herein by reference).

4.3            Amended and Restated By-Laws (filed as Exhibit 3.2 to the Annual
               Report on Form 10-K for the year ended July 1, 2000 and filed on
               September 22, 2000 (SEC File No. 000-29309) and incorporated
               herein by reference).

4.4            1999 Stock Plan (filed as Exhibit 4.4 to the Registration
               Statement on Form S-8 (SEC File No. 333-35310) and incorporated
               herein by reference).

4.5            Amendment No. 1 to the 1999 Stock Plan (filed as Exhibit 4.5 to
               the Registration Statement on Form S-8 (SEC File No. 333-66458)
               and incorporated herein by reference).

4.6            Amendment No. 2 to the 1999 Stock Plan, as amended.

4.7            Amendment No. 3 to the 1999 Stock Plan, as amended.

5.1            Opinion of Testa, Hurwitz & Thibeault, LLP.

23.1           Consent of Arthur Andersen LLP.

23.2           Consent of Testa, Hurwitz & Thibeault, LLP (included in Exhibit
               5.1).

24.1           Power of Attorney (included as part of the signature page to this
               Registration Statement).
[{"type": "S-8", "sequence": "1", "filename": "ds8.txt", "description": "FORM S-8", "secsgml_size_bytes": 12443}]
{"company-data": {"conformed-name": "MATRIXONE INC", "cik": "0000786998", "assigned-sic": "7372", "irs-number": "020372301", "state-of-incorporation": "DE", "fiscal-year-end": "0630"}, "filing-values": {"form-type": "S-8", "act": "33", "file-number": "333-81176", "film-number": "02514281"}, "business-address": {"street1": "TWO EXECUTIVE DR", "city": "CHEMSFORD", "state": "MA", "zip": "01824"}, "mail-address": {"street1": "TWO EXECUTIVE DRIVE", "city": "CHELMSFORD", "state": "MA", "zip": "01824"}, "former-company": {"former-conformed-name": "ADRA SYSTEMS INC", "date-changed": "19971024"}}
As filed with the Securities and Exchange Commission on January 22, 2002
                                                        Registration No.333-____

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

                      SECURITIES AND EXCHANGE COMMISSION
                            WASHINGTON, D.C.  20549

                                   FORM S-8

                         REGISTRATION STATEMENT UNDER
                          THE SECURITIES ACT OF 1933

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

        Delaware                                         02-0372301
  (State or Other Jurisdiction of           (I.R.S. Employer Identification No.)
  Incorporation or Organization)

                                MatrixOne, Inc.
                               210 Littleton Road
                               Westford, MA 01886
              (Address of Principal Executive Offices) (Zip Code)
                              ____________________

                          1999 Stock Plan, as amended
                            (Full Title of the Plan)

                              ____________________

                               Mark F. O'Connell
                      President & Chief Executive Officer
                                MatrixOne, Inc.
                               210 Littleton Road
                               Westford, MA 01886
                    (Name and Address of Agent For Service)

                                 (978) 589-4000
         (Telephone Number, Including Area Code, of Agent For Service)

                         _____________________________

                                    Copy to:

                           Gordon H. Hayes, Jr., Esq.
                        TESTA, HURWITZ & THIBEAULT, LLP
                                125 High Street
                          Boston, Massachusetts 02110
                                 (617) 248-7000

                        CALCULATION OF REGISTRATION FEE

================================================================================
Proposed         Proposed
                                                                         Maximum           Maximum
                                                Amount to be          Offering Price      Aggregate            Amount of
Title of Securities to be Registered             Registered             Per Share      Offering Price      Registration Fee (3)
------------------------------------             ----------             ---------      --------------      --------------------
1999 Stock Plan, as amended
Common Stock (Par Value $.01 Per Share)              43,213              $11.70(1)     $    505,592.10            $    46.51
                                                     19,500              $11.50(1)     $    224,250.00            $    20.63
                                                    120,000              $12.86(1)     $  1,543,200.00            $   141.97
                                                     50,000              $14.39(1)     $    719,500.00            $    66.19
                                                  2,767,287              $14.625(2)    $ 40,471,572.38            $ 3,723.38
                                                  ---------              ---------     ---------------            ----------
TOTAL:                                            3,000,000                            $ 43,464,114.48            $ 3,998.70
_________________________________________

(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.

(2)  The price of $14.625 per share, which is the average of the high and low
     prices of the Common Stock of the Registrant reported on the Nasdaq
     National Market on January 17, 2002, is set forth solely for purposes of
     calculating the filing fee pursuant to Rule 457(c) and has been used for
     those shares without a fixed exercise price.

(3)  Calculated pursuant to Section 6(b) of the Securities Act of 1933.

================================================================================
This Registration Statement registers additional securities of the same
class as other securities for which registration statements filed on Form S-8,
SEC File Nos. 333-66458 and 333-35310, of the Registrant are effective. Pursuant
to General Instruction E, the Registrant incorporates the information contained
in the Registrant's Registration Statements on Form S-8 (SEC File Nos. 333-66458
and 333-35310).

                                    PART II

               INFORMATION REQUIRED IN THE REGISTRATION STATEMENT

Item 8.  Exhibits.

Exhibit No.    Description of Exhibit
-----------    ----------------------

4.1            Specimen certificate for shares of the Registrant's common stock,
               $.01 par value per share (filed as Exhibit 4.1 to the
               Registration Statement on Form S-1 (SEC File No. 333-92731) and
               incorporated herein by reference).

4.2            Amended and Restated Certificate of Incorporation (filed as
               Exhibit 3.1 to the Annual Report on Form 10-K for the year ended
               July 1, 2000 and filed on September 22, 2000 (SEC File No. 000-
               29309) and incorporated herein by reference).

4.3            Amended and Restated By-Laws (filed as Exhibit 3.2 to the Annual
               Report on Form 10-K for the year ended July 1, 2000 and filed on
               September 22, 2000 (SEC File No. 000-29309) and incorporated
               herein by reference).

4.4            1999 Stock Plan (filed as Exhibit 4.4 to the Registration
               Statement on Form S-8 (SEC File No. 333-35310) and incorporated
               herein by reference).

4.5            Amendment No. 1 to the 1999 Stock Plan (filed as Exhibit 4.5 to
               the Registration Statement on Form S-8 (SEC File No. 333-66458)
               and incorporated herein by reference).

4.6            Amendment No. 2 to the 1999 Stock Plan, as amended.

4.7            Amendment No. 3 to the 1999 Stock Plan, as amended.

5.1            Opinion of Testa, Hurwitz & Thibeault, LLP.

23.1           Consent of Arthur Andersen LLP.

23.2           Consent of Testa, Hurwitz & Thibeault, LLP (included in Exhibit
               5.1).

24.1           Power of Attorney (included as part of the signature page to this
               Registration Statement).

                                       2
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 Town of Westford, Commonwealth of Massachusetts, on this
22nd day of January, 2002.

                                      MATRIXONE, INC.

                                      By:  /s/ Mark F. O'Connell
                                         -----------------------
                                           Mark F. O'Connell
                                           President and Chief Executive Officer

                        POWER OF ATTORNEY AND SIGNATURES

     The undersigned officers and directors of MatrixOne, Inc., hereby
constitute and appoint Mark F. O'Connell and Maurice L. Castonguay, and each of
them singly, our true and lawful attorneys-in-fact, with full power to them and
each of them singly, to sign for us in our names in the capacities indicated
below, any amendments to this Registration Statement on Form S-8 (including
post-effective amendments), and to file the same, with all exhibits thereto
and other documents in connection therewith, with the Securities and Exchange
Commission, and generally to do all things in our names and on our behalf in
our capacities as officers and directors to enable MatrixOne, Inc., to comply
with the provisions of the Securities Act of 1933, as amended, hereby ratifying
and confirming our signatures as they may be signed by our said attorneys, or
any of them, to said Registration Statement and all amendments thereto.

     Pursuant to the requirements of the Securities Act of 1933, this
Registration Statement has been signed below by the following persons in the
capacities and on the dates indicated.
Signature                         Title(s)                                         Date
     ---------                         --------                                         ----
/s/ Mark F. O'Connell                  President, Chief Executive Officer               January 22, 2002
-----------------------------          and Director (Principal Executive Officer)
Mark F. O'Connell

/s/ Maurice L. Castonguay              Chief Financial Officer, Senior Vice             January 22, 2002
-----------------------------          President of Finance and Administration
Maurice L. Castonguay                  and Treasurer (Principal Financial and
                                       Accounting Officer)

/s/ W. Patrick Decker                  Director                                         January 22, 2002
-----------------------------
W. Patrick Decker

/s/ Daniel J. Holland                  Director                                         January 22, 2002
-----------------------------
Daniel J. Holland

/s/ James F. Morgan                    Director                                         January 22, 2002
-----------------------------
James F. Morgan

/s/ Charles R. Stuckey, Jr.            Director                                         January 22, 2002
-----------------------------
Charles R. Stuckey, Jr.
3
EXHIBIT INDEX

Exhibit No.    Description of Exhibit
-----------    ----------------------

4.1            Specimen certificate for shares of the Registrant's common stock,
               $.01 par value per share (filed as Exhibit 4.1 to the
               Registration Statement on Form S-1 (SEC File No. 333-92731) and
               incorporated herein by reference).

4.2            Amended and Restated Certificate of Incorporation (filed as
               Exhibit 3.1 to the Annual Report on Form 10-K for the year ended
               July 1, 2000 and filed on September 22, 2000 (SEC File No. 000-
               29309) and incorporated herein by reference).

4.3            Amended and Restated By-Laws (filed as Exhibit 3.2 to the Annual
               Report on Form 10-K for the year ended July 1, 2000 and filed on
               September 22, 2000 (SEC File No. 000-29309) and incorporated
               herein by reference).

4.4            1999 Stock Plan (filed as Exhibit 4.4 to the Registration
               Statement on Form S-8 (SEC File No. 333-35310) and incorporated
               herein by reference).

4.5            Amendment No. 1 to the 1999 Stock Plan (filed as Exhibit 4.5 to
               the Registration Statement on Form S-8 (SEC File No. 333-66458)
               and incorporated herein by reference).

4.6            Amendment No. 2 to the 1999 Stock Plan, as amended.

4.7            Amendment No. 3 to the 1999 Stock Plan, as amended.

5.1            Opinion of Testa, Hurwitz & Thibeault, LLP.

23.1           Consent of Arthur Andersen LLP.

23.2           Consent of Testa, Hurwitz & Thibeault, LLP (included in Exhibit
               5.1).

24.1           Power of Attorney (included as part of the signature page to this
               Registration Statement).