<PAGE>
 
             As filed with the Securities and Exchange Commission
                                on May 14, 1999

                                         Registration No. 333-_____
================================================================================

                      SECURITIES AND EXCHANGE COMMISSION
                            Washington, D.C. 20549

                                   FORM S-8

                         REGISTRATION STATEMENT UNDER
                          THE SECURITIES ACT OF 1933

                          BANYAN SYSTEMS INCORPORATED
            (Exact Name of Registrant as Specified in Its Charter)

                                 MASSACHUSETTS
        (State or Other Jurisdiction of Incorporation or Organization)

                                  04-2798394
                    (I.R.S. Employer Identification Number)


120 FLANDERS ROAD, WESTBORO, MASSACHUSETTS                    01581
(Address of Principal Executive Offices)                     (Zip Code)

                          NON-QUALIFIED STOCK OPTION
                           (Full Title of the Plan)

                             MARK G. BORDEN, ESQ.
                               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)



                        CALCULATION OF REGISTRATION FEE

<TABLE>
<CAPTION>
========================================================================================== 
    Title Of                          Proposed          Proposed       
   Securities          Amount          Maximum           Maximum       
      To Be            To Be          Offering          Aggregate          Amount Of    
   Registered        Registered    Price Per Share    Offering Price    Registration Fee 
------------------------------------------------------------------------------------------ 
<S>                  <C>           <C>                <C>               <C>    
Common Stock         150,000 shares    12.375 (1)        1,856,250 (1)       $516.04
$.01 par value
------------------------------------------------------------------------------------------
========================================================================================== 
</TABLE>

(1)  Estimated solely for the purpose of calculating the registration fee and
     based upon the average of the high and low sale prices of the Common Stock
     on the Nasdaq National Market on May 10, 1999 in accordance with the Rules
     457(c) and 457(h) of the Securities Act of 1933.
<PAGE>
 
PART I.  INFORMATION REQUIRED IN THE SECTION 10(a) PROSPECTUS

          The information required by Part I of Form S-8 is included in
documents sent or given to the recipient of the Non-Qualified Stock Option from
Banyan Systems Incorporated (the "Registrant") pursuant to Rule 428(b)(1) of the
Securities Act of 1933, as amended (the "Securities Act").

PART II. INFORMATION REQUIRED IN THE REGISTRATION STATEMENT

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

          The Registrant is subject to the informational and reporting
requirements of Sections 13(a), 14 and 15(d) of the Securities Exchange Act of
1934, as amended (the "Exchange Act") and in accordance therewith files reports,
proxy statements and other information with the Securities and Exchange
Commission (the "Commission"). The following documents, which are filed with the
Commission, are incorporated in this Registration Statement by reference:

          (1)  The Registrant's latest annual report filed pursuant to Sections
     13(a) or 15(d) of the Exchange Act, or the latest prospectus filed pursuant
     to Rule 424(b) under the Securities Act that contains audited financial
     statements for the Registrant's latest fiscal year for which such
     statements have been filed.

          (2)  All other reports filed pursuant to Sections 13(a) or 15(d) of
     the Exchange Act since the end of the fiscal year covered by the annual
     report or the prospectus referred to in (1) above.

          (3)  The description of the common stock of the Registrant, $.01 par
     value per share (the "Common Stock"), contained in a Registration Statement
     filed under Section 12 of the Exchange Act, including any amendment or
     report filed for the purpose of updating such description.

          All documents subsequently filed by the Registrant pursuant to
Sections 13(a), 13(c), 14, and 15(d) of the Exchange Act, prior to the filing of
a post-effective amendment which indicates that all shares of Common Stock
offered hereby have been sold or which deregisters all shares of Common Stock
then remaining unsold, shall be deemed to be incorporated by reference herein
and to be part hereof from the date of the filing of such documents.

     Item 4.  Description of Securities
              -------------------------

          Not applicable.

     Item 5.  Interests of Named Experts and Counsel
              --------------------------------------

                                      II-1
<PAGE>
 
          Not applicable.


     Item 6.  Indemnification
              ---------------

          Section 67 of Chapter 156B of the Massachusetts General Laws ("Section
67") provides that a corporation may indemnify its directors and officers to the
extent specified in or authorized by (i) the articles of organization, (ii) a 
by-law adopted by the stockholders, or (iii) a vote adopted by the holders of a
majority of the shares of stock entitled to vote on the election of directors.
In all instances, the extent to which a corporation provides indemnification to
its directors and officers under Section 67 is optional. In its Second Amended
and Restated Articles of Organization the Registrant has elected to commit to
provide indemnification to its directors and officers in specified
circumstances. Generally, Article 6 of the Registrant's Second Amended and
Restated Articles of Organization indemnifies directors and officers of the
Registrant against liabilities and expenses arising out of legal proceedings
brought against them by reason of their status or service as directors or
officers or by reason of their agreeing to serve, at the request of the
Registrant, as a director or officer of, or in a similar capacity with, another
organization or in any capacity with respect to any employee benefit plan of the
Registrant. Under this provision, a director or officer of the Registrant shall
be indemnified by the Registrant for all expenses, judgments, fines and amounts
paid in settlement of such proceedings, even if he or she is not successful on
the merits, if he or she acted in good faith and in a manner he or she
reasonably believed to be in the best interests of the Registrant.

          The Registrant's Second Amended and Restated Articles of Organization
establish the presumption that the director or officer has met the applicable
standard of conduct required for indemnification. The indemnification above
shall be made unless the Registrant determines, by clear and convincing
evidence, that the applicable standard of conduct has not been met. Such a
determination may be made by a majority of a quorum of the directors,
independent legal counsel, the stockholders, or a court of competent
jurisdiction. The Board of Directors shall authorize advancing litigation
expenses to a director or officer at his request upon receipt of an undertaking
by such director or officer to repay such expenses if it is ultimately
determined that he or she is not entitled to indemnification for such expenses.

          The Registrant's Second Amended and Restated Articles of Organization
also provide that, in the event of a determination by the Registrant that a
director or officer did not meet the standard of conduct required for
indemnification, or if the Registrant fails to make an indemnification payment
or an advance of expenses within 60 days after such payment is claimed by a
director or officer, such director or officer may petition a court to make an
independent determination of whether such director or officer is entitled to
indemnification. The Registrant's Second Amended and Restated Articles of
Organization explicitly provide for partial indemnification of costs and
expenses in the event that a director of officer is not entitled to full
indemnification.

                                      II-2
<PAGE>
 
          Article 6 of the Registrant's Second Amended and Restated Articles of
Organization also eliminates the personal liability of the Registrant's
directors to the Registrant or its stockholders for monetary damages for breach
of a director's fiduciary duty, except to the extent Chapter 156B of the
Massachusetts General Laws prohibits the elimination or limitation of such
liability.

          The Registrant has purchased a general liability insurance policy
which covers certain liabilities of directors and officers of the Registrant
arising out of claims based on acts or omissions in their capacity as directors
or officers.

     Item 7.   Exemption from Registration Claimed
               -----------------------------------

          Not Applicable.

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

          The Exhibit Index immediately preceding the exhibits is incorporated
herein by reference.

     Item 9.   Undertakings
               ------------

          1.   The 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, 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.

          2.  The 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 in the initial bona fide offering thereof.

                                      II-3
<PAGE>
 
          3.  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, unenforce able. 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-4
<PAGE>
 
                                  SIGNATURES

     Pursuant to the requirements of the Securities Act, the Registrant
certifies that it has reasonable grounds to believe that it meets all of the
requirements for filing on Form S-8 and has duly caused this Registration
Statement to be signed on its behalf by the undersigned, thereunto duly
authorized, in the Town of Westboro, Commonwealth of Massachusetts on this 14th
day of May, 1999.

 
                                        BANYAN SYSTEMS INCORPORATED



                                        By:  /s/ William P. Ferry
                                             --------------------
                                               William P. Ferry
                                               Chairman of the Board, President
                                               and Chief Executive Officer


                               POWER OF ATTORNEY

     We, the undersigned officers and directors of Banyan Systems Incorporated,
hereby severally constitute William P. Ferry, Richard M. Spaulding and Mark G.
Borden, 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
officers and directors to enable Banyan Systems Incorporated to comply with 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.

                                      II-5
<PAGE>
 
     Pursuant to the requirements of the Securities Act, this Registration
Statement has been signed below by the following persons in the capacities and
on the dates indicated.

 
     Signature                          Title                  Date
     -----------                        -----
/s/ William P. Ferry           Chairman of the Board,      May 14, 1999
----------------------------   President and Chief 
William P. Ferry               Executive Officer   
                               (Principal Executive
                               Officer)             
                               
 
/s/ Richard M. Spaulding       Vice President, Chief       May 14, 1999
----------------------------   Financial Officer,
Richard M. Spaulding           Treasurer and Clerk
                               (Principal Financial
                               Officer and Principal
                               Accounting Officer)
 
/s/ G. Leonard Baker, Jr.      Director                    May 14, 1999 
----------------------------                                           
G. Leonard Baker, Jr.                                                  

/s/ John F. Burton             Director                    May 14, 1999
----------------------------                                           
John F. Burton                                                         

/s/ David C. Mahoney           Director                    May 14, 1999
----------------------------                                           
David C. Mahoney                                                       

/s/ Fontaine K. Richardson     Director                    May 14, 1999
----------------------------                                           
Fontaine K. Richardson                                                 

/s/ David N. Strohm            Director                    May 14, 1999
----------------------------                                           
David N. Strohm                                                        

/s/ Robert M. Wadsworth        Director                    May 14, 1999 
----------------------------
Robert M. Wadsworth
<PAGE>
 
                                 EXHIBIT INDEX
                                 -------------


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

   4 (1)  Specimen Certificate for shares of Common Stock of the Registrant

   5      Opinion of Hale and Dorr LLP

  10      Non-Qualified Stock Option Agreement dated February 1, 1999 granted by
          the Registrant to Scott Silk.

  23.1    Consent of Hale and Dorr LLP (included in Exhibit 5)

  23.2    Consent of PricewaterhouseCoopers LLP

  24      Power of Attorney (included on the signature page of this Registration
          Statement)


______________

(1)  Incorporated herein by reference from the Registrant's Registration
     Statement on Form S-1 (File No. 33-49194).