EXHIBIT 99.1

                               Pegasystems Inc.
                                101 Main Street
                              Cambridge, MA 02142

              Letter to Commission Pursuant To Temporary Note 3T

                                March 27, 2002

Securities and Exchange Commission
450 Fifth Street, N.W.
Washington, D.C. 20549-0408

Ladies and Gentlemen:

   Pursuant to Temporary Note 3T to Article 3 of Regulation S-X, Pegasystems
Inc. has obtained a letter of representation from Arthur Andersen LLP
("Andersen") stating that the December 31, 1999 audit was subject to their
quality control system for the U.S. accounting and auditing practice to provide
reasonable assurance that the engagement was conducted in compliance with
professional standards, and that there was appropriate continuity of Andersen
personnel working on the audit, availability of national office consultation,
and availability of personnel at foreign affiliates of Andersen to conduct the
relevant portions of the audit.

Very truly yours,

Pegasystems Inc.

/s/ Christopher Sullivan

Christopher Sullivan
Senior Vice President, Chief Financial Officer, and Treasurer