<PAGE>

     As filed with the Securities and Exchange Commission on June 28, 2000
                                                 Registration No. 333-__________
================================================================================

                      SECURITIES AND EXCHANGE COMMISSION
                           Washington, D. C.  20549

                                   FORM S-8

            REGISTRATION STATEMENT UNDER THE SECURITIES ACT OF 1933

                        PERITUS SOFTWARE SERVICES, INC.
            (Exact Name of Registrant as Specified in Its Charter)

Massachusetts                                                   04-3126919
(State or Other Jurisdiction of                              (I.R.S. Employer
Incorporation or Organization)                            Identification Number)

112 Turnpike Road, Suite 111, Westborough, Massachusetts           01581
(Address of Principal Executive Offices)                        (Zip Code)

           1997 DIRECTOR STOCK OPTION PLAN, AS AMENDED AND RESTATED
                           (Full Title of the Plan)

                               John D. Giordano
        President, Chief Executive Officer and Chief Financial Officer
                        PERITUS SOFTWARE SERVICES, INC.
                         112 Turnpike Road, Suite 111
                       Westborough, Massachusetts  01581
                    (Name and Address of Agent for Service)

                                (508) 870-0963
         (Telephone Number, Including Area Code, of Agent for Service)

                        CALCULATION OF REGISTRATION FEE

<TABLE>
<CAPTION>
-----------------------------------------------------------------------------------------------------------------------
                                               Proposed Maximum
Title of Securities     Amount to be          Offering Price Per            Proposed Maximum              Amount of
to be Registered         Registered                  Share              Aggregate Offering Price       Registration Fee
-------------------     ------------          ------------------        ------------------------       ----------------
-----------------------------------------------------------------------------------------------------------------------
<S>                    <C>                  <C>                        <C>                           <C>
Common Stock,             400,000                  $0.31 (1)                   $124,000 (1)                $32.74
$.01 par value
-----------------------------------------------------------------------------------------------------------------------
</TABLE>


  (1) Estimated solely for the purpose of calculating the registration fee, and
based upon the average of the bid and asked price of the Registrant's Common
Stock on the over-the-counter market on June 26, 2000 in accordance with Rules
457(c) and 457(h) under the Securities Act of 1933, as amended.
<PAGE>

PART I.  INFORMATION REQUIRED IN THE SECTION 10(a) PROSPECTUS

     The information required by Part I is included in documents sent or given
to participants in the Registrant's 1997 Director Stock Option Plan, as Amended
and Restated, 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

Statement of Incorporation by Reference

     This Registration Statement on Form S-8 incorporates by reference the
contents of the Registration Statement on Form S-8, File No. 333-35259, filed by
the Registrant on September 10, 1997, relating to the Registrant's 1997 Director
Stock Option Plan.

     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 on file with the
Commission, are incorporated in this Registration Statement by reference:

          (1) The Registrant's latest annual report filed pursuant to Section
          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 Section 13(a) or 15(d) of the
          Exchange Act since the end of the fiscal year covered by the document
          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 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.  Any statement
contained in a document incorporated or deemed to be incorporated by reference
herein shall be deemed to be modified or superseded for purposes of this
Registration Statement to the extent that a statement contained herein or in any
other subsequently filed document which also is or is deemed to be incorporated
by reference herein modifies or supersedes such statement.  Any statement so
modified or superseded shall not be deemed, except as so modified or superseded,
to constitute a part of this Registration Statement.

                                       2
<PAGE>

     Item 4.  Description of Securities.

     Not applicable.

     Item 5.  Interests of Named Experts and Counsel.

     Not applicable.

     Item 6.  Indemnification of Directors and Officers.

     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 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 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 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 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, a court of competent jurisdiction or a
majority vote of a quorum of the outstanding shares of stock (which quorum shall
consist of stockholders who are not parties to the suit). 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 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 Restated Articles of Organization explicitly provide for partial
indemnification of costs and expenses in the event that a director or officer is
not entitled to full indemnification.

                                       3
<PAGE>

     Article 6 of the Registrant's 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 such elimination or limitation is
prohibited by Chapter 156B of the Massachusetts General Laws.

     The Registrant has purchased and maintains insurance coverage under a
policy insuring directors and officers of the Registrant against certain
liabilities which they may incur as directors or officers of the Registrant.

     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:

               (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;

               (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 (i) and (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 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

                                       4
<PAGE>

          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 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.

     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 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.

                                       5
<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
Westborough, Commonwealth of Massachusetts, on this 13th day of June, 2000.


                              PERITUS SOFTWARE SERVICES, INC.

                              By:      /s/ John D. Giordano
                                 ---------------------------------
                                 John D. Giordano
                                 President, Chief Executive Officer and
                                 Chief Financial Officer


                       POWER OF ATTORNEY AND SIGNATURES

  We, the undersigned officers and directors of Peritus Software Services, Inc.
hereby severally constitute and appoint John D. Giordano, Eugene J. DiDonato and
Peter B. Tarr, 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 Peritus Software Services, Inc. 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.

                                       6
<PAGE>

     Pursuant to the requirements of the Securities Act, 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/ John D. Giordano                   President, Chief Executive Officer,    June 13, 2000
-------------------------------------  Chief Financial Officer and Director
John D. Giordano                       (Principal Executive Officer and
                                       Principal Financial Officer)

/s/ Patrick Manning                    Corporate Controller                   June 13, 2000
-------------------------------------  (Principal Accounting Officer)
Patrick Manning

/s/ Dominic K. Chan                    Director                               June 13, 2000
-------------------------------------
Dominic K. Chan

                                       Director
-------------------------------------
Axel Leblois

/s/ Johan Magnusson                    Director                               June 13, 2000
-------------------------------------
Johan Magnusson

/s/ Roland D. Pampel                   Director                               June 13, 2000
-------------------------------------
Roland D. Pampel

/s/ Andrew Youniss                     Director                               June 13, 2000
-------------------------------------
Andrew Youniss
</TABLE>

                                       7
<PAGE>

                                 EXHIBIT INDEX

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

3.1 (1)   Restated Articles of Organization of the Registrant.

3.2 (1)   Amended and Restated By-Laws of the Registrant.

4.1 (1)   Specimen certificate for shares of the Registrant's common stock, $.01
          par value per share.

5.1       Opinion of Hale and Dorr LLP.

10.1      1997 Director Stock Option Plan, as Amended and Restated.

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

23.2      Consent of PricewaterhouseCoopers LLP.

24.1      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, as amended (File No. 333-27087).
[{"type": "S-8", "sequence": "1", "filename": "0001.txt", "description": "FORM S-8", "secsgml_size_bytes": 18436}]
{"company-data": {"conformed-name": "PERITUS SOFTWARE SERVICES INC", "cik": "0001011632", "assigned-sic": "7371", "irs-number": "043126919", "state-of-incorporation": "MA", "fiscal-year-end": "1231"}, "filing-values": {"form-type": "S-8", "act": "33", "file-number": "333-40358", "film-number": "663879"}, "business-address": {"street1": "TWO FEDERAL STREET", "city": "BILLERICA", "state": "MA", "zip": "01821", "phone": "9786700800"}, "mail-address": {"street1": "TWO FEDERAL STREET", "city": "BILLERICA", "state": "MA", "zip": "01821"}}
As filed with the Securities and Exchange Commission on June 28, 2000
                                                 Registration No. 333-__________
================================================================================

                      SECURITIES AND EXCHANGE COMMISSION
                           Washington, D. C.  20549

                                   FORM S-8

            REGISTRATION STATEMENT UNDER THE SECURITIES ACT OF 1933

                        PERITUS SOFTWARE SERVICES, INC.
            (Exact Name of Registrant as Specified in Its Charter)

Massachusetts                                                   04-3126919
(State or Other Jurisdiction of                              (I.R.S. Employer
Incorporation or Organization)                            Identification Number)

112 Turnpike Road, Suite 111, Westborough, Massachusetts           01581
(Address of Principal Executive Offices)                        (Zip Code)

           1997 DIRECTOR STOCK OPTION PLAN, AS AMENDED AND RESTATED
                           (Full Title of the Plan)

                               John D. Giordano
        President, Chief Executive Officer and Chief Financial Officer
                        PERITUS SOFTWARE SERVICES, INC.
                         112 Turnpike Road, Suite 111
                       Westborough, Massachusetts  01581
                    (Name and Address of Agent for Service)

                                (508) 870-0963
         (Telephone Number, Including Area Code, of Agent for Service)

                        CALCULATION OF REGISTRATION FEE
-----------------------------------------------------------------------------------------------------------------------
                                               Proposed Maximum
Title of Securities     Amount to be          Offering Price Per            Proposed Maximum              Amount of
to be Registered         Registered                  Share              Aggregate Offering Price       Registration Fee
-------------------     ------------          ------------------        ------------------------       ----------------
-----------------------------------------------------------------------------------------------------------------------
Common Stock,             400,000                  $0.31 (1)                   $124,000 (1)                $32.74
$.01 par value
-----------------------------------------------------------------------------------------------------------------------
(1) Estimated solely for the purpose of calculating the registration fee, and
based upon the average of the bid and asked price of the Registrant's Common
Stock on the over-the-counter market on June 26, 2000 in accordance with Rules
457(c) and 457(h) under the Securities Act of 1933, as amended.
PART I.  INFORMATION REQUIRED IN THE SECTION 10(a) PROSPECTUS

     The information required by Part I is included in documents sent or given
to participants in the Registrant's 1997 Director Stock Option Plan, as Amended
and Restated, 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

Statement of Incorporation by Reference

     This Registration Statement on Form S-8 incorporates by reference the
contents of the Registration Statement on Form S-8, File No. 333-35259, filed by
the Registrant on September 10, 1997, relating to the Registrant's 1997 Director
Stock Option Plan.

     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 on file with the
Commission, are incorporated in this Registration Statement by reference:

          (1) The Registrant's latest annual report filed pursuant to Section
          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 Section 13(a) or 15(d) of the
          Exchange Act since the end of the fiscal year covered by the document
          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 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.  Any statement
contained in a document incorporated or deemed to be incorporated by reference
herein shall be deemed to be modified or superseded for purposes of this
Registration Statement to the extent that a statement contained herein or in any
other subsequently filed document which also is or is deemed to be incorporated
by reference herein modifies or supersedes such statement.  Any statement so
modified or superseded shall not be deemed, except as so modified or superseded,
to constitute a part of this Registration Statement.

                                       2
Item 4.  Description of Securities.

     Not applicable.

     Item 5.  Interests of Named Experts and Counsel.

     Not applicable.

     Item 6.  Indemnification of Directors and Officers.

     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 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 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 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 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, a court of competent jurisdiction or a
majority vote of a quorum of the outstanding shares of stock (which quorum shall
consist of stockholders who are not parties to the suit). 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 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 Restated Articles of Organization explicitly provide for partial
indemnification of costs and expenses in the event that a director or officer is
not entitled to full indemnification.

                                       3
Article 6 of the Registrant's 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 such elimination or limitation is
prohibited by Chapter 156B of the Massachusetts General Laws.

     The Registrant has purchased and maintains insurance coverage under a
policy insuring directors and officers of the Registrant against certain
liabilities which they may incur as directors or officers of the Registrant.

     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:

               (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;

               (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 (i) and (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 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

                                       4
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 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.

     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 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.

                                       5
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
Westborough, Commonwealth of Massachusetts, on this 13th day of June, 2000.

                              PERITUS SOFTWARE SERVICES, INC.

                              By:      /s/ John D. Giordano
                                 ---------------------------------
                                 John D. Giordano
                                 President, Chief Executive Officer and
                                 Chief Financial Officer

                       POWER OF ATTORNEY AND SIGNATURES

  We, the undersigned officers and directors of Peritus Software Services, Inc.
hereby severally constitute and appoint John D. Giordano, Eugene J. DiDonato and
Peter B. Tarr, 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 Peritus Software Services, Inc. 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.

                                       6
Pursuant to the requirements of the Securities Act, this Registration
Statement has been signed by the following persons in the capacities and on the
dates indicated.
Signature                                Title                      Date
-------------------------------------  -------------------------------------  --------------
/s/ John D. Giordano                   President, Chief Executive Officer,    June 13, 2000
-------------------------------------  Chief Financial Officer and Director
John D. Giordano                       (Principal Executive Officer and
                                       Principal Financial Officer)

/s/ Patrick Manning                    Corporate Controller                   June 13, 2000
-------------------------------------  (Principal Accounting Officer)
Patrick Manning

/s/ Dominic K. Chan                    Director                               June 13, 2000
-------------------------------------
Dominic K. Chan

                                       Director
-------------------------------------
Axel Leblois

/s/ Johan Magnusson                    Director                               June 13, 2000
-------------------------------------
Johan Magnusson

/s/ Roland D. Pampel                   Director                               June 13, 2000
-------------------------------------
Roland D. Pampel

/s/ Andrew Youniss                     Director                               June 13, 2000
-------------------------------------
Andrew Youniss
7
EXHIBIT INDEX

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

3.1 (1)   Restated Articles of Organization of the Registrant.

3.2 (1)   Amended and Restated By-Laws of the Registrant.

4.1 (1)   Specimen certificate for shares of the Registrant's common stock, $.01
          par value per share.

5.1       Opinion of Hale and Dorr LLP.

10.1      1997 Director Stock Option Plan, as Amended and Restated.

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

23.2      Consent of PricewaterhouseCoopers LLP.

24.1      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, as amended (File No. 333-27087).