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                                                                       EXHIBIT 5
                                                                       ---------



                                 February 26, 1999



Actuate Software Corporation
999 Baker Way
San Mateo, California 94404


          Re:  Actuate Software Corporation (the "Company")
               Registration Statement for
               an aggregate of 838,967 Shares of Common Stock

Ladies and Gentlemen:

  We refer to your registration on Form S-8 (the "Registration Statement") under
the Securities Act of 1933, as amended, of (i) 688,967 shares of Common Stock
available for issuance under the Company's 1998 Equity Incentive Plan, and (ii)
150,000 shares of Common Stock available for issuance under the Company's 1998
Employee Stock Purchase Plan.  We advise you that, in our opinion, when such
shares have been issued and sold pursuant to the applicable provisions of the
1998 Equity Incentive Plan and the 1998 Employee Stock Purchase Plan and in
accordance with the Registration Statement, such shares will be validly issued,
fully paid and nonassessable shares of Actuate Software Corporation's Common
Stock.

  We hereby consent to the filing of this opinion as an exhibit to the
Registration Statement.

                                 Very truly yours,
                                 /s/Gunderson Dettmer Stough Villeneuve Franklin
                                 & Hachigian, LLP


                                 Gunderson Dettmer Stough Villeneuve Franklin &
                                 Hachigian, LLP
