FIRST AMENDMENT TO EMPLOYMENT AGREEMENT

         This First  Amendment to  Employment  Agreement  (the  "Amendment")  is
entered into  effective as of December 3, 1999, by and between  Fair,  Isaac and
Company, Inc. ("Company") and Thomas G. Grudnowski ("Employee").

         WHEREAS,  Company and  Employee  entered into an  Employment  Agreement
dated August 23, 1999 (the "Agreement"); and

         WHEREAS, pursuant to the Agreement, Company has issued 10,000 shares of
its Common Stock to Employee  subject to certain  restrictions  (the "Restricted
Stock"), and

         WHEREAS,  Company and  Employee  desire to amend the  Agreement  as set
forth herein;

         THEREFORE they have agreed as follows:

1. Section 2.8.4 of the Agreement is hereby amended to read as follows:

         Additional  Option Grant. The Company hereby grants Employee options to
acquire an additional  40,000 shares of the Company's Common Stock pursuant to a
Stock  Option  Agreement  to  be  entered  into  between  Company  and  Employee
simultaneously with the execution of this Amendment.  The Exercise Price for the
options  granted  pursuant to this Paragraph shall be equal to the closing price
of the  Company's  Common Stock as quoted by the New York Stock  Exchange on the
date of this  Amendment,  i.e.  December 3, 1999. All such options shall vest on
January 1, 2000, and shall expire on December 3, 2009.

2. The Restricted  Stock  previously  issued by the Company to Employee shall be
cancelled.  Employee  shall not be liable  for the par value of such  Restricted
Stock and no dividends have been or shall be paid on such Restricted Stock.

         Except as expressly amended hereby,  the Agreement shall remain in full
force and effect.

                                                                   EXHIBIT 10.43




FIRST AMENDMENT TO EMPLOYMENT AGREEMENT                              Page 2 of 2

         IN WITNESS  WHEREOF,  the  Company  has  caused  this  Amendment  to be
executed by its duly authorized officer and Employee has executed this Amendment
as of the day and year first above written:


                                        FAIR, ISAAC AND COMPANY, INC.

                                        By: ____________________________________

                                        Its: Senior Vice President and Secretary


                                        EMPLOYEE:

                                        ________________________________________
                                                 Thomas G. Grudnowski