<PAGE>   1



As filed with the Securities and Exchange Commission on February 5, 1998.
                                              Registration No. 333- __________

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


                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549

                                    FORM S-8

                             REGISTRATION STATEMENT
                                    UNDER THE
                             SECURITIES ACT OF 1933


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


        Massachusetts                                 04-3085209
-------------------------------          ------------------------------------
(State or other jurisdiction of          (I.R.S. Employer Identification No.)
incorporation or organization)


38 Sidney Street, Cambridge, Massachusetts                 02139
--------------------------------------------------------------------------------
(Address of Principal Executive Offices)                 (Zip Code)


                       401(K) SAVINGS AND RETIREMENT PLAN
--------------------------------------------------------------------------------
                            (Full Title of the Plan)


                           John M. Westcott, Jr., Esq.
--------------------------------------------------------------------------------
                              c/o Hale and Dorr LLP
                                 60 State Street
                           Boston, Massachusetts 02109
                     (Name and Address of Agent for Service)


                                 (617) 526-6000
--------------------------------------------------------------------------------
          (Telephone Number, Including Area Code, of Agent For Service)


<PAGE>   2



                         CALCULATION OF REGISTRATION FEE
<TABLE>
<CAPTION>




====================================================================================================================================
                                                               Proposed                   Proposed
Title of                                                        Maximum                    Maximum
Securities                           Amount                    Offering                   Aggregate                    Amount
to be                                 to be                    Price Per                  Offering                of Registration
Registered                         Registered                  Share (1)                  Price (1)                   Fee (1)
------------------------------------------------------------------------------------------------------------------------------------
<S>                              <C>                             <C>                      <C>                           <C>
Common Stock,
$.001 par value                  100,000 shares                  $2.25                    $225,000                      $67
====================================================================================================================================
</TABLE>

(1)  Estimated solely for the purpose of calculating the registration fee
     pursuant to Rule 457(c) and (h) and based on the average of the reported
     high and low sale prices of the registrant's Common Stock on the Nasdaq
     National Market on January 29, 1998.


                                        2

<PAGE>   3



                     Statement of Incorporation by Reference

     This Registration Statement on Form S-8 (the "Registration Statement")
incorporates by reference the contents of the Registration Statement on Form
S-8, File No. 33-94988, filed by OraVax, Inc., a Delaware corporation (the
"Company"), with the Securities and Exchange Commission on July 26, 1995,
relating to the Company's 401(k) Savings and Retirement Plan.



                                        3

<PAGE>   4



                                   SIGNATURES




     Pursuant to the requirements of the Securities Act of 1933, the Company
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 Boston, Commonwealth of Massachusetts, on the 30th
day of January, 1998.

                                            ORAVAX, INC.


                                            By:  /s/ Lance K. Gordon
                                                 --------------------------
                                                 Lance K. Gordon,
                                                 President and
                                                 Chief Executive Officer


                                POWER OF ATTORNEY

     We, the undersigned Directors and Officers of the Company hereby constitute
Lance K. Gordon and John M. Westcott, Jr., and each of them singly, our true and
lawful attorneys with full power to them, and each of them singly, to sign for
us and in our names in the capacities indicated below, the Registration
Statement on Form S-8 filed herewith and any and all subsequent amendments to
said Registration Statement, and generally to do all such things in our names
and behalf in our capacities as Directors and Officers to enable OraVax, Inc. to
comply with all requirements of the Securities Act of 1933, as amended, and all
requirements of the Securities and Exchange Commission, hereby ratifying and
confirming our signatures as they may be signed by said attorneys, or any of
them, to said Registration Statement and any 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.


                                        4

<PAGE>   5




SIGNATURE                                TITLE               DATE



(i) Principal executive                                      )
    officer and principal                                    )
    financial and accounting                                 )
    officer:                                                 )
                                                             )
                                                             )
  /s/ Lance K. Gordon                    President and       )
--------------------------------         Chief Executive     )
Lance K. Gordon                          Officer             )
                                                             )
                                                             )
                                                             )
                                                             )
(ii)     A majority of the                                   )
         Board of Directors:                                 )
                                                             )
                                                             )
  /s/ Lance K. Gordon                    Director            ) January 30, 1998
--------------------------------                             )
Lance K. Gordon                                              )
                                                             )
                                                             )
  /s/ C. Boyd Clarke                     Director            )
--------------------------------                             )
C. Boyd Clarke                                               )
                                                             )
                                                             )
  /s/ Andre L. Lamotte                   Director            )
--------------------------------                             )
Andre L. Lamotte                                             )
                                                             )
                                                             )
  /s/ Douglas MacMaster                  Director            )
--------------------------------                             )
Douglas MacMaster                                            )
                                                             )
                                                             )
  /s/ Allen Misher                       Director            )
--------------------------------                             )
Allen Misher                                                 )
                                                             )


                                        5

<PAGE>   6



                                  EXHIBIT INDEX




EXHIBIT NO.                    DESCRIPTION                     PAGE

  4.1*        Second Amended and Restated Certificate           --
              of Incorporation of the Registrant.

  4.2*        Amended and Restated By-Laws of the               --
              Registrant

  5.1         Opinion of Hale and Dorr LLP.                     6

  23.1         Consent of Coopers & Lybrand L.L.P.              8

  23.2        Consent of Hale and Dorr LLP (included in         6
              Exhibit 5.1).

  24          Power of Attorney (included on page               3
              3 of this Registration Statement).


---------

*    Incorporated herein by reference to the Company's Registration Statement on
     Form S-1, as amended (File No. 33-90936).
[{"type": "S-8", "sequence": "1", "description": "ORAVAX, INC.", "secsgml_size_bytes": 9696}]
{"company-data": {"conformed-name": "ORAVAX INC /DE/", "cik": "0000900122", "assigned-sic": "2836", "irs-number": "043085209", "state-of-incorporation": "DE", "fiscal-year-end": "1231"}, "filing-values": {"form-type": "S-8", "act": "33", "file-number": "333-45639", "film-number": "98522291"}, "business-address": {"street1": "38 SIDNEY ST 4TH FLOOR", "city": "CAMBRIDGE", "state": "MA", "zip": "02139", "phone": "6175266000"}}
1

As filed with the Securities and Exchange Commission on February 5, 1998.
                                              Registration No. 333- __________

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

                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549

                                    FORM S-8

                             REGISTRATION STATEMENT
                                    UNDER THE
                             SECURITIES ACT OF 1933

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

        Massachusetts                                 04-3085209
-------------------------------          ------------------------------------
(State or other jurisdiction of          (I.R.S. Employer Identification No.)
incorporation or organization)

38 Sidney Street, Cambridge, Massachusetts                 02139
--------------------------------------------------------------------------------
(Address of Principal Executive Offices)                 (Zip Code)

                       401(K) SAVINGS AND RETIREMENT PLAN
--------------------------------------------------------------------------------
                            (Full Title of the Plan)

                           John M. Westcott, Jr., Esq.
--------------------------------------------------------------------------------
                              c/o Hale and Dorr LLP
                                 60 State Street
                           Boston, Massachusetts 02109
                     (Name and Address of Agent for Service)

                                 (617) 526-6000
--------------------------------------------------------------------------------
          (Telephone Number, Including Area Code, of Agent For Service)
2

                         CALCULATION OF REGISTRATION FEE
====================================================================================================================================
                                                               Proposed                   Proposed
Title of                                                        Maximum                    Maximum
Securities                           Amount                    Offering                   Aggregate                    Amount
to be                                 to be                    Price Per                  Offering                of Registration
Registered                         Registered                  Share (1)                  Price (1)                   Fee (1)
------------------------------------------------------------------------------------------------------------------------------------
Common Stock,
$.001 par value                  100,000 shares                  $2.25                    $225,000                      $67
====================================================================================================================================
(1)  Estimated solely for the purpose of calculating the registration fee
     pursuant to Rule 457(c) and (h) and based on the average of the reported
     high and low sale prices of the registrant's Common Stock on the Nasdaq
     National Market on January 29, 1998.

                                        2
3

                     Statement of Incorporation by Reference

     This Registration Statement on Form S-8 (the "Registration Statement")
incorporates by reference the contents of the Registration Statement on Form
S-8, File No. 33-94988, filed by OraVax, Inc., a Delaware corporation (the
"Company"), with the Securities and Exchange Commission on July 26, 1995,
relating to the Company's 401(k) Savings and Retirement Plan.

                                        3
4

                                   SIGNATURES

     Pursuant to the requirements of the Securities Act of 1933, the Company
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 Boston, Commonwealth of Massachusetts, on the 30th
day of January, 1998.

                                            ORAVAX, INC.

                                            By:  /s/ Lance K. Gordon
                                                 --------------------------
                                                 Lance K. Gordon,
                                                 President and
                                                 Chief Executive Officer

                                POWER OF ATTORNEY

     We, the undersigned Directors and Officers of the Company hereby constitute
Lance K. Gordon and John M. Westcott, Jr., and each of them singly, our true and
lawful attorneys with full power to them, and each of them singly, to sign for
us and in our names in the capacities indicated below, the Registration
Statement on Form S-8 filed herewith and any and all subsequent amendments to
said Registration Statement, and generally to do all such things in our names
and behalf in our capacities as Directors and Officers to enable OraVax, Inc. to
comply with all requirements of the Securities Act of 1933, as amended, and all
requirements of the Securities and Exchange Commission, hereby ratifying and
confirming our signatures as they may be signed by said attorneys, or any of
them, to said Registration Statement and any 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.

                                        4
5

SIGNATURE                                TITLE               DATE

(i) Principal executive                                      )
    officer and principal                                    )
    financial and accounting                                 )
    officer:                                                 )
                                                             )
                                                             )
  /s/ Lance K. Gordon                    President and       )
--------------------------------         Chief Executive     )
Lance K. Gordon                          Officer             )
                                                             )
                                                             )
                                                             )
                                                             )
(ii)     A majority of the                                   )
         Board of Directors:                                 )
                                                             )
                                                             )
  /s/ Lance K. Gordon                    Director            ) January 30, 1998
--------------------------------                             )
Lance K. Gordon                                              )
                                                             )
                                                             )
  /s/ C. Boyd Clarke                     Director            )
--------------------------------                             )
C. Boyd Clarke                                               )
                                                             )
                                                             )
  /s/ Andre L. Lamotte                   Director            )
--------------------------------                             )
Andre L. Lamotte                                             )
                                                             )
                                                             )
  /s/ Douglas MacMaster                  Director            )
--------------------------------                             )
Douglas MacMaster                                            )
                                                             )
                                                             )
  /s/ Allen Misher                       Director            )
--------------------------------                             )
Allen Misher                                                 )
                                                             )

                                        5
6

                                  EXHIBIT INDEX

EXHIBIT NO.                    DESCRIPTION                     PAGE

  4.1*        Second Amended and Restated Certificate           --
              of Incorporation of the Registrant.

  4.2*        Amended and Restated By-Laws of the               --
              Registrant

  5.1         Opinion of Hale and Dorr LLP.                     6

  23.1         Consent of Coopers & Lybrand L.L.P.              8

  23.2        Consent of Hale and Dorr LLP (included in         6
              Exhibit 5.1).

  24          Power of Attorney (included on page               3
              3 of this Registration Statement).

---------

*    Incorporated herein by reference to the Company's Registration Statement on
     Form S-1, as amended (File No. 33-90936).