EX-99.906CERT

                                  CERTIFICATION

      Walter G. Sall, Chief Executive Officer, and Gary H. Goldschmidt, Chief
Financial Officer of The Gateway Trust (the "Registrant"), each certify to the
best of his knowledge that:

      1. The Registrant's periodic report on Form N-CSR for the period ended
June 30, 2005 (the "Form N-CSR") fully complies with the requirements of
Sections 15(d) of the Securities Exchange Act of 1934, as amended; and

      2. The information contained in the Form N-CSR fairly presents, in all
material respects, the financial condition and results of operations of the
Registrant.

Chief Executive Officer                                 Chief Financial Officer
The Gateway Trust                                       The Gateway Trust

/s/ Walter G. Sall                                      /s/ Gary H. Goldschmidt
- ---------------------                                   -----------------------
Walter G. Sall                                          Gary H. Goldschmidt
Date: August 22, 2005                                   Date: August 22, 2005

A signed original of this written statement required by Section 906 of the
Sarbanes-Oxley Act of 2002 has been provided to The Gateway Trust and will be
retained by The Gateway Trust and furnished to the Securities and Exchange
Commission (the "Commission") or its staff upon request.

This certification is being furnished to the Commission solely pursuant to 18
U.S.C. Section 1350 and is not being filed as part of the Form N-CSR filed with
the Commission.