As filed with the Securities and Exchange Commission on May 10, 2002.

                                           Registration No. 333-________________

________________________________________________________________________________



                                  UNITED STATES
                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549



                                    FORM S-8


             REGISTRATION STATEMENT UNDER THE SECURITIES ACT OF 1933
                              --------------------

                      TRANSACTION SYSTEMS ARCHITECTS, INC.
              (Exact name of registrant as specified in its charter)

           Delaware                                              47-0772104
(State or other jurisdiction of                               (I.R.S. Employer
 incorporation or organization)                              Identification No.)

                             224 South 108th Avenue
                              Omaha, Nebraska 68154
          (Address of principal executive offices, including zip code)

                      Transaction Systems Architects, Inc.
                             1999 Stock Option Plan
                            (Full title of the plan)

                              David P. Stokes, Esq.
                          General Counsel and Secretary
                      Transaction Systems Architects, Inc.
                             224 South 108th Avenue
                              Omaha, Nebraska 68514
                                 (402) 334-5101
 (Name, address and telephone number, including area code, of agent for service)
                              --------------------

                                 with a copy to:

                             Albert G. McGrath, Jr.
                                Baker & McKenzie
                            2300 Trammell Crow Center
                                2001 Ross Avenue
                               Dallas, Texas 75201





                         CALCULATION OF REGISTRATION FEE
                                                                                    
====================================== ================ =================== ==================== ===================
                                                         Proposed maximum    Proposed maximum
                                        Amount to be      offering price    aggregate offering       Amount of
Title of securities to be registered   registered (1)     per share (2)          price (2)        registration fee
- -------------------------------------- ---------------- ------------------- -------------------- -------------------
Class A Common Stock, par value           1,000,000           $10.795           $10,795,000           $993.14
$.005 per share
====================================== ================ =================== ==================== ===================

(1)  Pursuant to Rule 416 promulgated under the Securities Act of 1933, as
     amended (the "Securities Act"), there are also being registered such
     additional shares of Class A Common Stock of Transaction Systems
     Architects, Inc. (the "Company"), par value $.005 per share (the "Common
     Stock"), as may become issuable pursuant to the anti-dilution provisions of
     the Transaction Systems Architects, Inc. 1999 Stock Option Plan (the "1999
     Stock Option Plan").
(2)  Estimated solely for the purpose of calculating the registration fee
     pursuant to Rule 457(c) and (h) promulgated under the Securities Act and is
     based upon the average of the high and low sale prices of the Common Stock
     on February 26, 2002, as reported on the National Association of Securities
     Dealers Automated Quotations system.



PART I INFORMATION REQUIRED IN THE SECTION 10(a) PROSPECTUS Item 1. Plan Information Not Applicable. Item 2. Registrant Information and Employee Plan Annual Information Not Applicable. PART II INFORMATION REQUIRED IN THE REGISTRATION STATEMENT Item 3. Incorporation of Documents by Reference This registration statement (the "Registration Statement") is being filed solely to register an additional 1,000,000 shares of Common Stock under the 1999 Stock Option Plan. Pursuant to General Instruction E to Form S-8, the contents of the Company's registration statements on Form S-8 (File No. 333-73027) as filed with the Securities and Exchange Commission (the "Commission") on February 26, 1999, Form S-8 (File No. 333-33728) as filed with the Commission on March 31, 2000, and on Form S-8 (File No. 333-59630) as filed with the Commission on April 27, 2001 are incorporated herein by reference, except as the same may be modified by the information set forth in this Registration Statement. Item 4. Description of Securities Not Applicable. Item 5. Interest of Named Experts and Counsel Not Applicable. Item 6. Indemnification of Directors and Officers Not Applicable. Item 7. Exemption from Registration Claimed Not Applicable. Item 8. Exhibits The following are filed as exhibits to this Registration Statement: Exhibit Description No. 5.1(1) Opinion of Baker & McKenzie 23.1(1) Consent of Arthur Andersen LLP 23.2(1) Consent of Baker & McKenzie (included in Exhibit 5.1) 24.1(1) Power of Attorney (included on the signature page of this Registration Statement) - ---------------- (1) Filed herewith. Item 9. Undertakings Not Applicable.

SIGNATURES Pursuant to the requirements of the Securities Act, the Company 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 Omaha, State of Nebraska, on February 27, 2002. TRANSACTION SYSTEMS ARCHITECTS, INC. /s/ DWIGHT G. HANSON By:-------------------------------------- Dwight G. Hanson, Chief Financial Officer, Treasurer and Senior Vice President POWER OF ATTORNEY Each person whose signature appears below hereby constitutes and appoints Dwight G. Hanson his true and lawful attorney-in-fact and agent, with full power of substitution and resubstitution for him and his name, place and stead, in any and all capacities, to sign any or all amendments (including pre- or post-effective amendments) to this Registration Statement, and to file the same, with all exhibits thereto, and other documents in connection therewith, with the Commission, and hereby grants to such attorney-in-fact and agent, full power and authority to do and perform each and every act and thing requisite and necessary to be done, as fully to all intents and purposes as he might or could do in person, hereby ratifying and confirming all that said attorney-in-fact and agent, or his substitute, may lawfully do or cause to be done by virtue hereof. Pursuant to the requirements of the Securities Act, this Registration Statement has been signed by the following persons in the capacities and on the date indicated. Signature Title Date /s/ GREGORY D. DERKACHT - ----------------------------------- President, Chief Executive Officer and February 27, 2002 Gregory D. Derkacht Director /s/ GREGORY J. DUMAN - ----------------------------------- Chairman of the Board and Director February 27, 2002 Gregory J. Duman /s/ LARRY G. FENDLEY - ----------------------------------- Interim Chief Operating Officer and Director February 27, 2002 Larry G. Fendley /s/ DWIGHT G. HANSON - ----------------------------------- Chief Financial Officer, Treasurer and February 27, 2002 Dwight G. Hanson Senior Vice President /s/ EDWARD C. FUXA - ----------------------------------- Chief Accounting Officer, Vice President February 27, 2002 Edward C. Fuxa and Controller /s/ JIM D. KEVER - ----------------------------------- Director February 27, 2002 Jim D. Kever /s/ ROGER K. ALEXANDER - ----------------------------------- Director February 27, 2002 Roger K. Alexander

EXHIBIT INDEX Exhibit Description No. 5.1(1) Opinion of Baker & McKenzie 23.1(1) Consent of Arthur Andersen LLP 23.2(1) Consent of Baker & McKenzie (included in Exhibit 5.1) 24.1(1) Power of Attorney (included on the signature page of this Registration Statement) - ---------------- (1) Filed herewith.

                                                                     EXHIBIT 5.1
                                BAKER & MCKENZIE
                                Attorneys at Law

                            2300 Trammell Crow Center
                                2001 Ross Avenue
                               Dallas, Texas 75201


                                February 27, 2002


Board of Directors
Transaction Systems Architects, Inc.
224 South 108th Avenue
Omaha, Nebraska 68154

Re:  Transaction Systems Architects, Inc. (the "Company")

Gentlemen:

    The Company has filed with the Securities and Exchange Commission (the
"Commission") a registration statement (the "Registration Statement") on Form
S-8 under the Securities Act of 1933, as amended (the "Act"). The Registration
Statement covers (a) 1,000,000 shares of Class A Common Stock, par value $.005
per share, of the Company (the "Common Stock"), which shares shall be issued
pursuant to the Transaction Systems Architects, Inc. 1999 Stock Option Plan, as
amended (the "1999 Stock Option Plan"), and (b) such additional shares of Common
Stock as may become issuable pursuant to the anti-dilution provisions of the
1999 Stock Option Plan (such shares collectively referred to as the
"Securities").

    We have acted as counsel to the Company in connection with the
preparation and filing of the Registration Statement. In rendering this opinion
we have examined such corporate records, documents and instruments of the
Company and such certificates of public officials, have received such
representations from officers of the Company, and have reviewed such questions
of law as in our judgment are necessary, relevant or appropriate to enable us to
render the opinion expressed below. In such examination, we have assumed the
genuineness of all signatures, the authenticity of all corporate records,
documents and instruments submitted to us as originals, the conformity to
original documents of all documents submitted to us as conformed, certified or
photostatic copies thereof, and the authenticity of the originals of such
conformed, certified or photostatic copies.

    Based upon such examination and review and upon representations made to
us by officers of the Company, we are of the opinion that upon issuance and
delivery of the Securities in accordance with the applicable terms and
conditions of the 1999 Stock Option Plan and upon receipt by the Company of the
full consideration for the Securities as determined pursuant to the 1999 Stock
Option Plan, the Securities will be legally issued, fully paid and
nonassessable.

    This firm consents to the filing of this opinion as an exhibit to the
Registration Statement. In giving such consent, we do not admit that we come
within the category of persons whose consent is required by Section 7 of the Act
or the rules and regulations of the Commission thereunder.

                                                Very truly yours,



                                                Baker & McKenzie



                                                                    EXHIBIT 23.1

Consent of independent public accountants

As independent public accountants, we hereby consent to the incorporation by
reference in this Registration Statement on Form S-8 of our report dated October
26, 2001, included in Transaction Systems Architects, Inc.'s Annual Report on
Form 10-K for the fiscal year ended September 30, 2001, and to all references to
our firm included in this Registration Statement.

Arthur Andersen LLP

Omaha, Nebraska,
February 27, 2002