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                                                                    EXHIBIT 5.01


                                 July 12, 2000



HNC Software Inc.
5935 Cornerstone Court West
San Diego, CA  92121-3728


Gentlemen/Ladies:

        At your request, we have examined the Registration Statement on Form S-8
(the "REGISTRATION Statement") to be filed by you with the Securities and
Exchange Commission (the "COMMISSION") on or about July 13, 2000, in connection
with the registration under the Securities Act of 1933, as amended, of an
aggregate of 232,259 shares of your Common Stock, $0.001 par value (the
"SHARES"), that are subject to issuance by you upon the exercise of stock
options (collectively, the "ASSUMED OPTIONS") assumed by you under (a) the eHNC
Inc. 1999 Equity Incentive Plan, as amended (the "eHNC EQUITY PLAN"); and (b)
the eHNC Inc. 1999 Executive Equity Incentive Plan (the "eHNC EXECUTIVE PLAN").
The eHNC Equity Plan and the eHNC Executive Plan are (collectively referred to
herein as the "ASSUMED PLANS" and each as an "ASSUMED PLAN.")

        In rendering this opinion, we have examined the following:

        (1)    your registration statement on Form 8-A filed with the Commission
               on May 26, 1995, together with the order of effectiveness issued
               by the Commission therefor on June 20, 1995;

        (2)    the Registration Statement, together with the Exhibits filed as a
               part thereof, including without limitation the eHNC Equity Plan,
               the eHNC Executive Plan, the forms of stock option agreements and
               stock option exercise agreements used under the eHNC Equity Plan
               and the eHNC Executive Plan that are attached as exhibits to the
               Registration Statement (collectively, the "ASSUMED OPTION
               AGREEMENTS"), which you have represented to us constitute the
               plans and agreements that apply to the Assumed Options;

        (3)    the prospectus prepared in connection with the Registration
               Statement;

        (4)    the minutes of meetings and actions by written consent of the
               stockholders and Board of Directors that are contained in your
               minute books that are in our possession;

        (5)    a certificate from your transfer agent of recent date verifying
               the number of your issued and outstanding shares of your capital
               stock;

        (7)    the management certificate you delivered to us in connection with
               the merger of eHNC Inc. addressed to us, dated July 12, 2000,
               executed by you and containing certain representations and
               warranties;

        (8)    your Restated Certificate of Incorporation as amended, and Bylaws
               as amended, both included as exhibits to the Registration
               Statement; and

        (9)    the Certificate of Ownership and Plan of Merger filed by you with
               the Delaware Secretary of State on July 7, 2000 with respect to
               the merger of eHNC Inc. into HNC Software Inc.




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        In our examination of documents for purposes of this opinion, we have
assumed, and express no opinion as to, the genuineness of all signatures on
original documents, the authenticity of all documents submitted to us as
originals, the conformity to originals of all documents submitted to us as
copies, the legal capacity of all natural persons executing the same, the lack
of any undisclosed terminations, modifications, waivers or amendments to any
documents reviewed by us and the due execution and delivery of all documents
where due execution and delivery are prerequisites to the effectiveness thereof.

        As to matters of fact relevant to this opinion, we have relied solely
upon our examination of the documents referred to above and have assumed the
current accuracy and completeness of the information obtained from records
referred to above. We have made no independent investigation or other attempt to
verify the accuracy of any of such information or to determine the existence or
non-existence of any other factual matters; however, we are not aware of any
facts that would cause us to believe that the opinion expressed herein is not
accurate.

        We are admitted to practice law in the State of California, and we
express no opinion herein with respect to the effect of the laws of any
jurisdiction other than the existing laws of the United States of America, the
State of California and the General Corporation Law of the State of Delaware.

        Based upon the foregoing, it is our opinion that the Shares that may be
issued and sold by you upon the exercise of the Assumed Options, when issued and
sold in accordance with the applicable Assumed Plan and the applicable Assumed
Option Agreement, will be validly issued, fully paid and nonassessable.

        We consent to the use of this opinion as an exhibit to the Registration
Statement and further consent to all references to us, if any, in the
Registration Statement, the prospectus constituting a part thereof and any
amendments thereto.

        This opinion speaks only as of its date and we assume no obligation to
update this opinion should circumstances change after the date hereof.



                                        Very truly yours,



                                        /s/ FENWICK & WEST LLP





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