<PAGE>   1
   As filed with the Securities and Exchange Commission on February 20, 1998
                                             Registration No. __________________


================================================================================
                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549

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

                                    FORM S-8
                             REGISTRATION STATEMENT

                                      Under
                           The Securities Act of 1933

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

                                 MICROMUSE INC.

             (Exact name of registrant as specified in its charter)

<TABLE>
<S>                                  <C>                               <C>
        DELAWARE                               7372                        75-2649505
 (State or other jurisdiction        (Primary Standard Industrial         (IRS Employer
of incorporation or organization)     Classification Code Number)      Identification No.)
</TABLE>


                               139 TOWNSEND STREET
                         SAN FRANCISCO, CALIFORNIA 94107

               (Address of principal executive offices) (Zip Code)

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

                                 MICROMUSE INC.
                      1997 STOCK OPTION/STOCK ISSUANCE PLAN
                        1997 EMPLOYEE STOCK PURCHASE PLAN
                            (Full title of the Plans)

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

                              CHRISTOPHER J. DAWES
                      CHIEF EXECUTIVE OFFICER AND PRESIDENT
                                 MICROMUSE INC.
                               139 TOWNSEND STREET
                         SAN FRANCISCO, CALIFORNIA 94107

                     (Name and address of agent for service)
                                 (415) 538-9090

          (Telephone number, including area code, of agent for service)


                         CALCULATION OF REGISTRATION FEE

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


<TABLE>
<CAPTION>
         Title of                                    Proposed Maximum     Proposed Maximum
        Securities                       Amount          Offering             Aggregate         Amount of
          to be                          to be            Price               Offering        Registration
        Registered                    Registered(1)     per Share(2)          Price(2)             Fee
        ----------                    ----------        ---------             -----                ---
<S>                                <C>               <C>                  <C>                 <C>
1997 Stock Option/              
Stock Issuance Plan

Options to purchase
Common Stock                           2,493,771             N/A                 N/A               N/A
                                                                                                  
Common Stock (par value $.01)       2,493,771 shares         $12             $29,925,252         $8,828
                                                                                                  
Employee Stock Purchase Plan                                                                      
                                                                                                  
Common Stock (par value $.01)        300,000 shares          $12              $3,600,000         $1,062

     Aggregate Filing Fee                                                                        $9,890
                                                                                         
</TABLE>


(1)     This Registration Statement shall also cover any additional shares of
        Common Stock which become issuable under the 1997 Stock Option/Stock
        Issuance Plan and the 1997 Employee Stock Purchase Plan by reason of any
        stock dividend, stock split, recapitalization or other similar
        transaction effected without the receipt of consideration which results
        in an increase in the number of the outstanding shares of Common Stock
        of Micromuse Inc.

(2)     Calculated solely for purposes of this offering under Rule 457(h) of the
        Securities Act of 1933, as amended, on the basis of the fair market
        value per share of Common Stock of Micromuse Inc.


<PAGE>   2
                                     PART II
               INFORMATION REQUIRED IN THE REGISTRATION STATEMENT

Item 3.  Incorporation of Documents by Reference

        Micromuse Inc. (the "Registrant") hereby incorporates by reference into
        this Registration Statement the following documents previously filed
        with the Securities and Exchange Commission (the "SEC"):

        (a)    The Registrant's prospectus filed with the SEC pursuant to Rule
               424(b) of the Securities Act of 1933, as amended (the "1933
               Act"), in connection with the Registration Statement No.
               333-42177 on Form S-1 filed with the SEC on December 12, 1997,
               together with any and all amendments thereto, in which there is
               set forth audited consolidated financial statements for the
               Registrant's fiscal years ended September 30, 1995, 1996 and 
               1997 and unaudited condensed consolidated financial statements
               for the Registrants quarters ended December 31, 1996 and 1997; 
               and

        (b)    The description of the Registrant's outstanding Common Stock
               contained in the Registrant's Registration Statement No. 00-23783
               on Form 8-A filed with the SEC on February 12, 1998 pursuant to
               Section 12 of the Securities Exchange Act of 1934, as amended
               (the "1934 Act"), including any amendment or report filed for the
               purpose of updating such description.

        All reports and definitive proxy or information statements filed
        pursuant to Section 13(a), 13(c), 14 or 15(d) of the 1934 Act after the
        date of this Registration Statement and prior to the filing of a
        post-effective amendment which indicates that all securities offered
        hereby have been sold or which deregisters all securities then remaining
        unsold shall be deemed to be incorporated by reference into 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

        Section 145 of the Delaware General Corporation Law authorizes a court
to award or a corporation's board of directors to grant indemnification to
directors and officers in terms sufficiently broad to permit such
indemnification under certain circumstances for liabilities (including
reimbursement for expenses incurred) arising under the Securities Act of 1933,
as amended (the "1933 Act"). Article IX, Section 1, of the Registrant's Bylaws
provides for mandatory indemnification of its directors and officers and
permissible indemnification of employees and other agents to the maximum extent
permitted by the Delaware General Corporation Law. The Registrant's Restated
Certificate of Incorporation provides that, pursuant to Delaware law, its
directors shall not be liable for monetary damages for breach of the directors'
fiduciary duty as directors to the Company and its stockholders. This provision
in the Restated Certificate of Incorporation does not eliminate the directors'
fiduciary duty, and in appropriate circumstances equitable remedies such as
injunctive or other forms of non-monetary relief will remain available under
Delaware law. In addition, each director will continue to be subject to
liability for breach of the director's duty of loyalty to the Company for acts
or omissions not in good faith or involving intentional misconduct, for knowing
violations of law, for actions leading to improper personal benefit to the
director, and for payment of dividends or approval of stock repurchases or
redemptions that are unlawful under Delaware law. The provision also does not
affect a director's responsibilities under any other law, such as the federal
securities laws or state or federal environmental laws. The Registrant has
entered into Indemnification Agreements with its officers and directors. The
Indemnification Agreements provide the Registrant's officers and directors with
further indemnification to the maximum extent permitted by the Delaware General
Corporation Law.

        The Registrant's Bylaws provide that the Registrant shall indemnify its
directors and officers to the fullest extent permitted by Delaware law,
including in circumstances in which indemnification is otherwise discretionary
under Delaware law. The Registrant has also entered into indemnification
agreements with its officers and directors containing provisions that may
require the Company, among other things, to indemnify such officers and
directors against certain liabilities that may arise by reason of their status
or service as directors or officers (other than liabilities arising from willful
misconduct of a culpable nature), to advance their expenses incurred as a result
of any proceeding against them as to which they could be indemnified, and to
obtain directors' and officers' insurance if available on reasonable terms.


<PAGE>   3
Item 7.  Exemption from Registration Claimed

         Not Applicable.

Item 8.  Exhibits

<TABLE>
<CAPTION>
Exhibit Number    Exhibit
--------------    -------
<S>               <C>

     4              Instruments Defining Rights of Stockholders.  Reference is made to
                    Registrant's Registration Statement No. 00-23783 on Form 8-A, which 
                    is incorporated herein by reference pursuant to Item 3(b) of this 
                    Registration Statement.

     5              Opinion and consent of Gunderson Dettmer Stough Villeneuve Franklin &
                    Hachigian, LLP.

     23.1           Consent of KPMG Peat Marwick LLP, Independent Accountants.

     23.2           Consent of Gunderson Dettmer Stough Villeneuve Franklin & Hachigian,
                    LLP is contained in Exhibit 5.

     24             Power of Attorney.  Reference is made to page II-3 of this
                    Registration Statement.
</TABLE>

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 1933 Act, (ii) to
         reflect in the prospectus any facts or events arising after the
         effective date of this 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 this Registration Statement and (iii) to include any material
         information with respect to the plan of distribution not previously
         disclosed in this Registration Statement or any material change to such
         information in this Registration Statement; provided, however, that
         clauses (1)(i) and (1)(ii) shall not apply if the information required
         to be included in a post-effective amendment by those paragraphs is
         contained in periodic reports filed by the Registrant pursuant to
         Section 13 or Section 15(d) of the 1934 Act that are incorporated by
         reference into this Registration Statement; (2) that for the purpose of
         determining any liability under the 1933 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 and (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 Registrant's 1997 Stock
         Option/Stock Issuance Plan and/or 1997 Employee Stock Purchase Plan.

                  B. The undersigned Registrant hereby undertakes that, for
         purposes of determining any liability under the 1933 Act, each filing
         of the Registrant's annual report pursuant to Section 13(a) or Section
         15(d) of the 1934 Act that is incorporated by reference into this
         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 1933 Act may be permitted to directors, officers or controlling
         persons of the Registrant pursuant to the indemnification provisions
         summarized in Item 6 or otherwise, the Registrant has been advised
         that, in the opinion of the SEC, such indemnification is against public
         policy as expressed in the 1933 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 1933
         Act and will be governed by the final adjudication of such issue.


                                      II-2


<PAGE>   4
                                   SIGNATURES

        Pursuant to the requirements of the Securities Act of 1933, as amended,
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 City of San Francisco, State of California on this 12th
day of February, 1998.


                                      MICROMUSE INC.


                                      By:   /s/ Christopher J. Dawes
                                         -------------------------------
                                          Christopher J. Dawes
                                          President and Chief Executive Officer



                                POWER OF ATTORNEY

KNOW ALL PERSONS BY THESE PRESENTS:

        That the undersigned officers and directors of Micromuse Inc., a
Delaware corporation, do hereby constitute and appoint Christopher J. Dawes and
Stephen A. Allott, and either of them, the lawful attorneys-in-fact and agents
with full power and authority to do any and all acts and things and to execute
any and all instruments which said attorneys and agents, and either one of them,
determine may be necessary or advisable or required to enable said corporation
to comply with the Securities Act of 1933, as amended, and any rules or
regulations or requirements of the Securities and Exchange Commission in
connection with this Registration Statement. Without limiting the generality of
the foregoing power and authority, the powers granted include the power and
authority to sign the names of the undersigned officers and directors in the
capacities indicated below to this Registration Statement, to any and all
amendments, both pre-effective and post-effective, and supplements to this
Registration Statement, and to any and all instruments or documents filed as
part of or in conjunction with this Registration Statement or amendments or
supplements thereof, and either of the undersigned hereby ratifies and confirms
all that said attorneys and agents, or either one of them, shall do or cause to
be done by virtue hereof. This Power of Attorney may be signed in several
counterparts.

        IN WITNESS WHEREOF, each of the undersigned has executed this Power of
Attorney as of the date indicated.

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


<TABLE>
<CAPTION>
Signature                                             Title                                     Date
---------                                             -----                                     ----
<S>                                    <C>                                                <C>

/s/ Christopher J. Dawes               President, Chief Executive Officer and             February 12,1998
-----------------------------
Christopher J. Dawes                   Director (Principal Executive Officer)



/s/ Stephen A. Allott                  Chief FinancialOfficer,                            February 12, 1998
-----------------------------
Stephen A. Allott                      (Principal Financial and Accounting Officer)



/s/ Angela Dawes                       Director                                           February 12, 1998
-----------------------------
Angela Dawes
</TABLE>


                                      II-3


<PAGE>   5
<TABLE>
<CAPTION>
Signature                                             Title                                     Date
---------                                             -----                                     ----
<S>                                    <C>                                                <C>
/s/ Jeffrey M. Drazan                  Director                                           February 12, 1998
-----------------------------
Jeffrey M. Drazan



/s/ David C. Schwab                    Director                                           February 12, 1998
-----------------------------
David C. Schwab
</TABLE>


                                      II-4


<PAGE>   6
                                  EXHIBIT INDEX


<TABLE>
<CAPTION>
Exhibit Number    Exhibit
--------------    -------
<S>               <C>
     4              Instruments Defining Rights of Stockholders.  Reference is made to
                    Registrant's Registration Statement No. 00-23783 on Form 8-A, which
                    is incorporated herein by reference pursuant to Item 3(b) of this
                    Registration Statement.

     5              Opinion and consent of Gunderson Dettmer Stough Villeneuve Franklin &
                    Hachigian, LLP.

     23.1           Consent of KPMG Peat Marwick LLP, Independent Accountants.

     23.2           Consent of Gunderson Dettmer Stough Villeneuve Franklin & Hachigian,
                    LLP is contained in Exhibit 5.

     24             Power of Attorney.  Reference is made to page II-3 of this
                    Registration Statement.
</TABLE>
[{"type": "S-8", "sequence": "1", "description": "FORM S-8", "secsgml_size_bytes": 19750}]
{"company-data": {"conformed-name": "MICROMUSE INC", "cik": "0001036425", "assigned-sic": "7372", "irs-number": "943288385", "state-of-incorporation": "DE", "fiscal-year-end": "1231"}, "filing-values": {"form-type": "S-8", "act": "33", "file-number": "333-46649", "film-number": "98546524"}, "business-address": {"street1": "139 TOWNSEND ST", "street2": "MEZZANINE FLOOR", "city": "SAN FRANCISCO", "state": "CA", "zip": "94107"}, "mail-address": {"street1": "139 TOWNSEND STREET", "city": "SAN FRANCISCO", "state": "CA", "zip": "94107"}}
1
   As filed with the Securities and Exchange Commission on February 20, 1998
                                             Registration No. __________________

================================================================================
                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549

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

                                    FORM S-8
                             REGISTRATION STATEMENT

                                      Under
                           The Securities Act of 1933

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

                                 MICROMUSE INC.

             (Exact name of registrant as specified in its charter)
DELAWARE                               7372                        75-2649505
 (State or other jurisdiction        (Primary Standard Industrial         (IRS Employer
of incorporation or organization)     Classification Code Number)      Identification No.)
139 TOWNSEND STREET
                         SAN FRANCISCO, CALIFORNIA 94107

               (Address of principal executive offices) (Zip Code)

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

                                 MICROMUSE INC.
                      1997 STOCK OPTION/STOCK ISSUANCE PLAN
                        1997 EMPLOYEE STOCK PURCHASE PLAN
                            (Full title of the Plans)

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

                              CHRISTOPHER J. DAWES
                      CHIEF EXECUTIVE OFFICER AND PRESIDENT
                                 MICROMUSE INC.
                               139 TOWNSEND STREET
                         SAN FRANCISCO, CALIFORNIA 94107

                     (Name and address of agent for service)
                                 (415) 538-9090

          (Telephone number, including area code, of agent for service)

                         CALCULATION OF REGISTRATION FEE

================================================================================
Title of                                    Proposed Maximum     Proposed Maximum
        Securities                       Amount          Offering             Aggregate         Amount of
          to be                          to be            Price               Offering        Registration
        Registered                    Registered(1)     per Share(2)          Price(2)             Fee
        ----------                    ----------        ---------             -----                ---
1997 Stock Option/              
Stock Issuance Plan

Options to purchase
Common Stock                           2,493,771             N/A                 N/A               N/A
                                                                                                  
Common Stock (par value $.01)       2,493,771 shares         $12             $29,925,252         $8,828
                                                                                                  
Employee Stock Purchase Plan                                                                      
                                                                                                  
Common Stock (par value $.01)        300,000 shares          $12              $3,600,000         $1,062

     Aggregate Filing Fee                                                                        $9,890
(1)     This Registration Statement shall also cover any additional shares of
        Common Stock which become issuable under the 1997 Stock Option/Stock
        Issuance Plan and the 1997 Employee Stock Purchase Plan by reason of any
        stock dividend, stock split, recapitalization or other similar
        transaction effected without the receipt of consideration which results
        in an increase in the number of the outstanding shares of Common Stock
        of Micromuse Inc.

(2)     Calculated solely for purposes of this offering under Rule 457(h) of the
        Securities Act of 1933, as amended, on the basis of the fair market
        value per share of Common Stock of Micromuse Inc.
2
                                     PART II
               INFORMATION REQUIRED IN THE REGISTRATION STATEMENT

Item 3.  Incorporation of Documents by Reference

        Micromuse Inc. (the "Registrant") hereby incorporates by reference into
        this Registration Statement the following documents previously filed
        with the Securities and Exchange Commission (the "SEC"):

        (a)    The Registrant's prospectus filed with the SEC pursuant to Rule
               424(b) of the Securities Act of 1933, as amended (the "1933
               Act"), in connection with the Registration Statement No.
               333-42177 on Form S-1 filed with the SEC on December 12, 1997,
               together with any and all amendments thereto, in which there is
               set forth audited consolidated financial statements for the
               Registrant's fiscal years ended September 30, 1995, 1996 and 
               1997 and unaudited condensed consolidated financial statements
               for the Registrants quarters ended December 31, 1996 and 1997; 
               and

        (b)    The description of the Registrant's outstanding Common Stock
               contained in the Registrant's Registration Statement No. 00-23783
               on Form 8-A filed with the SEC on February 12, 1998 pursuant to
               Section 12 of the Securities Exchange Act of 1934, as amended
               (the "1934 Act"), including any amendment or report filed for the
               purpose of updating such description.

        All reports and definitive proxy or information statements filed
        pursuant to Section 13(a), 13(c), 14 or 15(d) of the 1934 Act after the
        date of this Registration Statement and prior to the filing of a
        post-effective amendment which indicates that all securities offered
        hereby have been sold or which deregisters all securities then remaining
        unsold shall be deemed to be incorporated by reference into 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

        Section 145 of the Delaware General Corporation Law authorizes a court
to award or a corporation's board of directors to grant indemnification to
directors and officers in terms sufficiently broad to permit such
indemnification under certain circumstances for liabilities (including
reimbursement for expenses incurred) arising under the Securities Act of 1933,
as amended (the "1933 Act"). Article IX, Section 1, of the Registrant's Bylaws
provides for mandatory indemnification of its directors and officers and
permissible indemnification of employees and other agents to the maximum extent
permitted by the Delaware General Corporation Law. The Registrant's Restated
Certificate of Incorporation provides that, pursuant to Delaware law, its
directors shall not be liable for monetary damages for breach of the directors'
fiduciary duty as directors to the Company and its stockholders. This provision
in the Restated Certificate of Incorporation does not eliminate the directors'
fiduciary duty, and in appropriate circumstances equitable remedies such as
injunctive or other forms of non-monetary relief will remain available under
Delaware law. In addition, each director will continue to be subject to
liability for breach of the director's duty of loyalty to the Company for acts
or omissions not in good faith or involving intentional misconduct, for knowing
violations of law, for actions leading to improper personal benefit to the
director, and for payment of dividends or approval of stock repurchases or
redemptions that are unlawful under Delaware law. The provision also does not
affect a director's responsibilities under any other law, such as the federal
securities laws or state or federal environmental laws. The Registrant has
entered into Indemnification Agreements with its officers and directors. The
Indemnification Agreements provide the Registrant's officers and directors with
further indemnification to the maximum extent permitted by the Delaware General
Corporation Law.

        The Registrant's Bylaws provide that the Registrant shall indemnify its
directors and officers to the fullest extent permitted by Delaware law,
including in circumstances in which indemnification is otherwise discretionary
under Delaware law. The Registrant has also entered into indemnification
agreements with its officers and directors containing provisions that may
require the Company, among other things, to indemnify such officers and
directors against certain liabilities that may arise by reason of their status
or service as directors or officers (other than liabilities arising from willful
misconduct of a culpable nature), to advance their expenses incurred as a result
of any proceeding against them as to which they could be indemnified, and to
obtain directors' and officers' insurance if available on reasonable terms.
3
Item 7.  Exemption from Registration Claimed

         Not Applicable.

Item 8.  Exhibits
Exhibit Number    Exhibit
--------------    -------
4              Instruments Defining Rights of Stockholders.  Reference is made to
                    Registrant's Registration Statement No. 00-23783 on Form 8-A, which 
                    is incorporated herein by reference pursuant to Item 3(b) of this 
                    Registration Statement.

     5              Opinion and consent of Gunderson Dettmer Stough Villeneuve Franklin &
                    Hachigian, LLP.

     23.1           Consent of KPMG Peat Marwick LLP, Independent Accountants.

     23.2           Consent of Gunderson Dettmer Stough Villeneuve Franklin & Hachigian,
                    LLP is contained in Exhibit 5.

     24             Power of Attorney.  Reference is made to page II-3 of this
                    Registration Statement.
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 1933 Act, (ii) to
         reflect in the prospectus any facts or events arising after the
         effective date of this 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 this Registration Statement and (iii) to include any material
         information with respect to the plan of distribution not previously
         disclosed in this Registration Statement or any material change to such
         information in this Registration Statement; provided, however, that
         clauses (1)(i) and (1)(ii) shall not apply if the information required
         to be included in a post-effective amendment by those paragraphs is
         contained in periodic reports filed by the Registrant pursuant to
         Section 13 or Section 15(d) of the 1934 Act that are incorporated by
         reference into this Registration Statement; (2) that for the purpose of
         determining any liability under the 1933 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 and (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 Registrant's 1997 Stock
         Option/Stock Issuance Plan and/or 1997 Employee Stock Purchase Plan.

                  B. The undersigned Registrant hereby undertakes that, for
         purposes of determining any liability under the 1933 Act, each filing
         of the Registrant's annual report pursuant to Section 13(a) or Section
         15(d) of the 1934 Act that is incorporated by reference into this
         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 1933 Act may be permitted to directors, officers or controlling
         persons of the Registrant pursuant to the indemnification provisions
         summarized in Item 6 or otherwise, the Registrant has been advised
         that, in the opinion of the SEC, such indemnification is against public
         policy as expressed in the 1933 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 1933
         Act and will be governed by the final adjudication of such issue.

                                      II-2
4
                                   SIGNATURES

        Pursuant to the requirements of the Securities Act of 1933, as amended,
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 City of San Francisco, State of California on this 12th
day of February, 1998.

                                      MICROMUSE INC.

                                      By:   /s/ Christopher J. Dawes
                                         -------------------------------
                                          Christopher J. Dawes
                                          President and Chief Executive Officer

                                POWER OF ATTORNEY

KNOW ALL PERSONS BY THESE PRESENTS:

        That the undersigned officers and directors of Micromuse Inc., a
Delaware corporation, do hereby constitute and appoint Christopher J. Dawes and
Stephen A. Allott, and either of them, the lawful attorneys-in-fact and agents
with full power and authority to do any and all acts and things and to execute
any and all instruments which said attorneys and agents, and either one of them,
determine may be necessary or advisable or required to enable said corporation
to comply with the Securities Act of 1933, as amended, and any rules or
regulations or requirements of the Securities and Exchange Commission in
connection with this Registration Statement. Without limiting the generality of
the foregoing power and authority, the powers granted include the power and
authority to sign the names of the undersigned officers and directors in the
capacities indicated below to this Registration Statement, to any and all
amendments, both pre-effective and post-effective, and supplements to this
Registration Statement, and to any and all instruments or documents filed as
part of or in conjunction with this Registration Statement or amendments or
supplements thereof, and either of the undersigned hereby ratifies and confirms
all that said attorneys and agents, or either one of them, shall do or cause to
be done by virtue hereof. This Power of Attorney may be signed in several
counterparts.

        IN WITNESS WHEREOF, each of the undersigned has executed this Power of
Attorney as of the date indicated.

        Pursuant to the requirements of the Securities Act of 1933, as amended,
this Registration Statement has been signed below by the following persons in
the capacities and on the dates indicated.
Signature                                             Title                                     Date
---------                                             -----                                     ----
/s/ Christopher J. Dawes               President, Chief Executive Officer and             February 12,1998
-----------------------------
Christopher J. Dawes                   Director (Principal Executive Officer)

/s/ Stephen A. Allott                  Chief FinancialOfficer,                            February 12, 1998
-----------------------------
Stephen A. Allott                      (Principal Financial and Accounting Officer)

/s/ Angela Dawes                       Director                                           February 12, 1998
-----------------------------
Angela Dawes
II-3
5
Signature                                             Title                                     Date
---------                                             -----                                     ----
/s/ Jeffrey M. Drazan                  Director                                           February 12, 1998
-----------------------------
Jeffrey M. Drazan

/s/ David C. Schwab                    Director                                           February 12, 1998
-----------------------------
David C. Schwab
II-4
6
                                  EXHIBIT INDEX
Exhibit Number    Exhibit
--------------    -------
4              Instruments Defining Rights of Stockholders.  Reference is made to
                    Registrant's Registration Statement No. 00-23783 on Form 8-A, which
                    is incorporated herein by reference pursuant to Item 3(b) of this
                    Registration Statement.

     5              Opinion and consent of Gunderson Dettmer Stough Villeneuve Franklin &
                    Hachigian, LLP.

     23.1           Consent of KPMG Peat Marwick LLP, Independent Accountants.

     23.2           Consent of Gunderson Dettmer Stough Villeneuve Franklin & Hachigian,
                    LLP is contained in Exhibit 5.

     24             Power of Attorney.  Reference is made to page II-3 of this
                    Registration Statement.