EX-99.906CERT
CERTIFICATION
PURSUANT TO SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002
In connection with the shareholder report of American Century Mutual Funds, Inc. (the "Registrant") on Form N-CSR for the period ending October 31, 2009 (the "Report"), we, the undersigned, certify, pursuant to Section 906 of the Sarbanes-Oxley Act of 2002, that:
| (1) | The Report fully complies with the requirements of Section 15(d) of the Securities Exchange Act of 1934; and |
| (2) | The information contained in the Report fairly presents, in all material respects, the financial condition and results of operations of the Registrant. |
| Date: | December 30, 2009 |
| By: | /s/ Jonathan S. Thomas |
| Jonathan S. Thomas | |
| President | |
| (chief executive officer) |
| By: | /s/ Robert J. Leach |
| Robert J. Leach | |
| Vice President, Treasurer, and | |
| Chief Financial Officer | |
| (chief financial officer) |