American Century Municipal Trust Prospectus Supplement Tax-Free Money Market Fund
Supplement dated August 1, 2010 ¡ Prospectus dated October 1, 2009

Effective August 1, 2010, the advisor waived 0.054% of the fund’s management fee. The advisor expects this waiver to continue for one year and cannot terminate it without consulting with the Board of Trustees.

©2010 American Century Proprietary Holdings, Inc. All rights reserved.

CL-SPL-69156  1008