<PAGE>
 
   As filed with the Securities and Exchange Commission on December 17, 1998

                                             REGISTRATION STATEMENT NO. 333-
================================================================================


                      SECURITIES AND EXCHANGE COMMISSION
                            WASHINGTON, D.C. 20549
                           _________________________

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

                             SEGUE SOFTWARE, INC.
            (Exact name of Registrant as specified in its charter)

              DELAWARE                                   95-4188982
     (State of incorporation)            (I.R.S. Employer Identification Number)

                               201 SPRING STREET
                        LEXINGTON, MASSACHUSETTS 02421
                               (781) 402 - 1000

  (Address, including zip code, and telephone number, including area code, of
                   Registrant's principal executive offices)

             SEGUE SOFTWARE, INC. 1998 EMPLOYEE STOCK OPTION PLAN

                           (Full Title of the Plan)

                           _________________________

                               STEPHEN B. BUTLER
                     PRESIDENT AND CHIEF EXECUTIVE OFFICER
                              SEGUE SOFTWARE, INC.
                               201 SPRING STREET
                         LEXINGTON, MASSACHUSETTS 02421
                                (781) 402 - 1000

 (Name, address, including zip code, and telephone number, including area code,
                             of agent for service)
                           _________________________

                                With a copy to:
                            Jeffrey C. Hadden, Esq.
                         Goodwin, Procter & Hoar  LLP
                                Exchange Place
                                53 State Street
                       Boston, Massachusetts 02109-2881
                                (617) 570-1000
                           _________________________

                        CALCULATION OF REGISTRATION FEE

<TABLE>
<CAPTION>
===========================================================================================================================
                                                                                    Proposed Maximum
Title of Securities Being        Amount to be     Proposed Maximum Offering            Aggregate              Amount of
 Registered                      Registered(1)         Price Per Share              Offering Price         Registration Fee
---------------------------------------------------------------------------------------------------------------------------
<S>                             <C>              <C>                               <C>                    <C>
Common Stock, par value $.01           7,202                        $ 0.75                 $     5,401.50         $    1.51
 per share                            15,826                          2.34                      37,032.84             10.30
                                       8,087                          4.21                      34,046.27              9.47
                                     968,885                         23.25(2)               22,526,576.25          6,262.39
                                   ---------                                               --------------         ---------
                                   1,000,000                                               $22,603,056.86         $6,284.00
 
===========================================================================================================================
</TABLE>

(1)  Additional shares issued or available for issuance under the Segue
     Software, Inc. 1998 Employee Stock Option Plan ( the "Stock Option Plan");
     plus such additional number of shares as may be required pursuant to the
     Stock Option Plan in the event of a stock dividend, stock split,
     recapitalization or other similar event.

(2)  This estimate is based on the average of the high and low sales prices on
     the Nasdaq National Market of the Common Stock of Segue Software, Inc. on
     December 14, 1998 pursuant to Rules 457(c) and (h) under the Securities Act
     of 1933, as amended, solely for purposes of determining the registration
     fee.

================================================================================
<PAGE>
 
                                    PART I

            INFORMATION REQUIRED IN THE SECTION 10(a) PROSPECTUSES

Item 1.   Plan Information.*
          ----------------  

Item 2.   Registrant Information and Employee Plan Annual Information.*
          -----------------------------------------------------------  


* Information required by Part I to be contained in the Section 10(a)
Prospectuses is omitted from this Registration Statement in accordance with Rule
428 under the Securities Act of 1933, as amended (the "Securities Act") and the
Introductory Note to Part I of Form S-8.



                                    PART II

              INFORMATION REQUIRED IN THE REGISTRATION STATEMENT


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

    Segue Software, Inc. (the "Company") hereby incorporates by reference the
documents listed in (a) through (c) below, which have previously been filed with
the Securities and Exchange Commission.

    (a) The Company's Annual Report on Form 10-K, containing audited financial
        statements for the fiscal year ended December 31, 1997, filed with the
        Securities and Exchange Commission (the "Commission") pursuant to
        Section 13(a) of the Securities Exchange Act of 1934, as amended (the
        "Exchange Act"), on March 30, 1998;

    (b) All other reports filed since December 31, 1997 pursuant to Section
        13(a) or 15(d) of the Exchange Act; and

    (c) The description of the Company's common stock contained in its
        Registration Statement on Form 8-A, filed with the Commission on
        February 16, 1996, as amended, under Section 12 of the Exchange Act and
        any amendments or reports filed for the purpose of updating such
        description.

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


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

    Not Applicable.


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

    Not Applicable.


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

    Subsection (a) of Section 145 of the Delaware General Corporation Law (the
"DGCL") empowers a corporation to indemnify any person who was or is a party or
is threatened to be made a party to any threatened, pending or completed action,
suit or proceeding, whether civil, criminal, administrative or investigative
(other than an action by or in the right of the corporation) by reason of the
fact that the person is or was a director, officer, employee or agent of the
corporation, or is or was serving at the request of the corporation as a
director, officer, employee or agent of another corporation, partnership, joint
venture, trust or other enterprise, against expenses (including attorneys'
fees), judgments, fines and amounts paid in settlement actually and reasonably
incurred by the person in connection with such action, suit or proceeding if the
person acted in good 
<PAGE>
 
faith and in a manner the person reasonably believed to be in or not opposed to
the best interests of the corporation, and, with respect to any criminal action
or proceeding, had no reasonable cause to believe the person's conduct was
unlawful. Under subsection (a) the termination of any action, suit or proceeding
by judgment, order, settlement, conviction or upon a plea of nolo contendere or
its equivalent, shall not, of itself, create a presumption that the person did
not act in good faith and in a manner which the person reasonably believed to be
in or not opposed to the best interests of the corporation, and, with respect to
any criminal action or proceeding, had reasonable cause to believe that the
person's conduct was unlawful.

    Subsection (b) of Section 145 of the DGCL empowers a corporation to
indemnify any person who was or is a party or is threatened to be made a party
to any threatened, pending or completed action or suit by or in the right of the
corporation to procure a judgment in its favor by reason of the fact that the
person is or was a director, officer, employee or agent of the corporation, or
is or was serving at the request of the corporation as a director, officer,
employee or agent of another corporation, partnership, joint venture, trust or
other enterprise against expenses (including attorneys' fees) actually and
reasonably incurred by the person in connection with the defense or settlement
of such action or suit if the person acted in good faith and in a manner the
person reasonably believed to be in or not opposed to the best interests of the
corporation and except that no indemnification shall be made in respect of any
claim, issue or matter as to which such person shall have been adjudged to be
liable to the corporation unless and only to the extent that the Court of
Chancery or the court in which such action or suit was brought shall determine
upon application that, despite the adjudication of liability but in view of all
the circumstances of the case, such person is fairly and reasonably entitled to
indemnity for such expenses which the Court of Chancery or such other court
shall deem proper.

    Subsection (d) of Section 145 of the DGCL permits indemnification under
subsections (a) and (b) of Section 145 only if authorized in the specific case
following a determination that the individual seeking indemnification has met
the standard of conduct required by the applicable subsection.  Such
determination shall be made (1) by a majority vote of the directors who are not
parties to such action, suit or proceeding, even though less than a quorum, or
(2) if there are no such directors, or if such directors so direct, by
independent legal counsel in a written opinion, or (3) by the stockholders.

    Section 145 further provides that to the extent a director or officer of a
corporation has been successful on the merits or otherwise in defense of any
action, suit or proceeding referred to in subsections (a) and (b) of Section
145, or in the defense of any claim, issue or matter therein, he or she shall be
indemnified against expenses (including attorneys' fees) actually and reasonably
incurred by him or her in connection therewith; that indemnification provided
for by Section 145 shall not be deemed exclusive of any other rights to which
the indemnified party may be entitled; that indemnification provided for by
Section 145 shall, unless otherwise provided when authorized or ratified,
continue as to a person who has ceased to be a director, officer, employee or
agent and shall inure to the benefit of such person's heirs, executors and
administrators; and that the corporation has the power to purchase and maintain
insurance on behalf of a director or officer of the corporation against any
liability asserted against him or her and incurred by him or her in any such
capacity, or arising out of his or her status as such whether or not the
corporation would have the power to indemnify him or her against such
liabilities under Section 145.

    Article VII of the Company's Amended and Restated Certificate of
Incorporation, as amended (the "Certificate"), and  Article V of the Company's
By-laws provides for indemnification by the Company, to the fullest extent
permitted by Section 145 of the DGCL, the same exists or may hereafter be
amended, of its directors, officers, and certain persons serving at the request
of the Company as a director, officer, employee or agent of another company, or
of a partnership, joint venture, trust or other enterprise, including service
with respect to an employee benefit plan (hereinafter "Indemnitee") against all
expense, liability and loss (including attorney's fees, judgments, fines, ERISA
excise taxes or penalties and amounts paid in settlement) reasonably incurred or
suffered by the Indemnitee in connection with the defense or settlement of any
threatened, pending or completed legal proceeding, whether civil, criminal,
administrative or investigative, in which said Indemnitee is involved by reason
of his relationship with the Company.

    Article VIII of the Company's Certificate provides that no director of the
Company shall be personally liable to the Company or its stockholders for
monetary damages  for breach of fiduciary duty as a director, except for
liability (i) for any breach of the director's duty of loyalty to the Company or
its stockholders, (ii) for acts or omissions not in good faith or which involve
intentional misconduct or a knowing violation of law, (iii) in respect of
certain unlawful dividend payments or stock redemptions or repurchases, or (iv)
for any transaction from which the director derived an improper personal
benefit.  In addition, the Certificate provides that if the DGCL is amended to
authorize the further elimination or limitation of the liability of directors,
then the liability of a director of the Corporation shall be eliminated or
limited to the fullest extent permitted by the DGCL as so amended.

                                       2
<PAGE>
 
Item 7.   Exemption from Registration Claimed.
          ----------------------------------- 

    Not applicable.


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

    The following is a complete list of exhibits filed or incorporated by
reference as part of this registration statement.

Exhibits
--------

    4.1  Segue Software, Inc. Amended and Restated Certificate of Incorporation
         (incorporated herein by reference to exhibit 3.2 of the Company's
         Registration Statement on Form S-1 (File No. 333-1488) as filed with
         the Commission on February 16, 1996).
    4.2  Segue Software, Inc. By-laws (incorporated herein by reference to
         exhibit 3.3 of the Company's Registration Statement on Form S-1 (File
         No. 333-1488) as filed with the Commission on February 16, 1996).
   *4.3  Segue Software, Inc. 1998 Employee Stock Option Plan.
   *5.1  Opinion of Goodwin, Procter & Hoar LLP as to the legality of the
         securities being registered.
   23.1  Consent of Goodwin, Procter & Hoar  LLP (included in Exhibit 5.1).
  *23.2  Consent of PricewaterhouseCoopers LLP.
   24.1  Powers of Attorney (included on page 5 of this registration statement).

         *Filed herewith

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;

            (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 and of the estimated
        maximum offering range may be reflected in the form of prospectus filed
        with the Commission pursuant to Rule 424(b) if, in the aggregate, the
        changes in volume and price represent no more than 20 percent change in
        the maximum aggregate offering price set forth in the "Calculation of
        Registration Fee" table in the effective registration statement.

            (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) above shall 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 Commission by the registrant pursuant to Section 13 or
    15(d) of the Exchange Act that are incorporated by reference 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.

                                       3
<PAGE>
 
    (b)     The undersigned registrant hereby undertakes that, for purposes of
        determining any liability under the Securities Act, each filing of the
        registrant's annual report pursuant to Section 13(a) or 15(d) of the
        Exchange Act (and, where applicable, each filing of an employee benefit
        plan's annual report pursuant to Section 15(d) of the Exchange Act) that
        is incorporated by reference in the registration statement shall be
        deemed to be a new registration statement relating to the securities
        offered therein, and the offering of such securities at that time shall
        be deemed to be the initial bona fide offering thereof.

    (c)     Insofar as indemnification for liabilities arising under the
        Securities Act may be permitted to directors, officers and controlling
        persons of the registrant pursuant to the foregoing provisions, or
        otherwise, the registrant has been advised that in the opinion of the
        Securities and Exchange Commission such indemnification is against
        public policy as expressed in the Securities Act, and is, therefore,
        unenforceable. In the event that a claim for indemnification against
        such liabilities (other than the payment by the registrant of expenses
        incurred or paid by a director, officer or controlling person of the
        registrant in the successful defense of any action, suit or proceeding)
        is asserted by such director, officer or controlling person in
        connection with the securities being registered, the registrant will,
        unless in the opinion of its counsel the matter has been settled by
        controlling precedent, submit to a court of appropriate jurisdiction the
        question whether such indemnification by it is against public policy as
        expressed in the Securities Act and will be governed by the final
        adjudication of such issue.

                                       4
<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 Lexington, Commonwealth of Massachusetts, on 
December 17, 1998.

                                    SEGUE SOFTWARE, INC.


                                    By:  /s/ Stephen B. Butler
                                         ---------------------
                                         Stephen B. Butler
                                         President and Chief Executive Officer


                               POWER OF ATTORNEY

    KNOW ALL MEN BY THESE PRESENTS, that we, the undersigned officers and
directors of Segue Software, Inc. hereby severally constitute Stephen B. Butler
and Carl D. Blandino, 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 filed
herewith and any and all amendments to said registration statement, and
generally to do all such things in our names and in our capacities as officers
and directors to enable Segue Software, Inc. to comply with the provisions of
the Securities Act of 1933 and all requirements of the Securities and Exchange
Commission, hereby ratifying and confirming our signatures as they may be signed
by our 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 date indicated.

<TABLE> 
<CAPTION> 
          SIGNATURE             CAPACITY                                DATE
          ---------             --------                                ----
<S>                     <C>                                          <C> 
/s/ Stephen B. Butler   President, Chief Executive Officer,          December 17, 1998
---------------------   Director (Principal Executive Officer)
Stephen B. Butler
 
/s/ Carl D. Blandino    Senior Vice President of Administration,     December 17, 1998
--------------------    Chief Financial Officer
Carl D. Blandino        (Principal Financial and Accounting Officer)


/s/ Leonard E. Baum     Director                                     December 17, 1998
-------------------
Leonard E. Baum


/s/ Ronald D. Fisher    Director                                     December 17, 1998
--------------------    
Ronald D. Fisher


/s/ John R. Levine       Director                                    December 17, 1998
------------------                                                       
John R. Levine


/s/ Howard L. Morgan     Director                                    December 17, 1998
--------------------                                                     
Howard L. Morgan


/s/ James H. Simons      Director                                    December 17, 1998
-------------------
James H. Simons

</TABLE> 

                                       5
<PAGE>
 
                                 EXHIBIT INDEX


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

   4.1     Segue Software, Inc. Amended and Restated Certificate of
           Incorporation (incorporated herein by reference to exhibit 3.2 of the
           Company's Registration Statement on Form S-1 (File No. 333-1488) as
           filed with the Commission on February 16, 1996).

   4.2     Segue Software, Inc. By-laws (incorporated herein by reference to
           exhibit 3.2 of the Company's Registration Statement on Form S-1 (File
           No. 333-1488) as filed with the Commission on February 16, 1996).

  *4.3     Segue Software, Inc. 1998 Employee Stock Option Plan.

  *5.1     Opinion of Goodwin, Procter & Hoar LLP as to the legality of the
           securities being registered.

  23.1     Consent of Goodwin, Procter & Hoar  LLP (included in Exhibit 5.1).

 *23.2     Consent of PricewaterhouseCoopers LLP.

  24.1     Powers of Attorney (included on page 5 of this registration
           statement).

           *Filed herewith