<TABLE> <S> <C>
<ARTICLE> 6
<LEGEND>
THIS SCHEDULE CONTAINS SUMMARY FINANCIAL INFORMATION EXTRACTED FROM THE
ANNUAL REPORT OF AMERICAN CENTURY MUTUAL FUNDS, INC. AND IS QUALIFIED
IN ITS ENTIRETY BY REFERENCE TO SUCH REPORT.
</LEGEND>
<CIK> 0000100334
<NAME> AMERICAN CENTURY MUTUAL FUNDS, INC.
<SERIES>
<NUMBER> 111
<NAME> HERITAGE FUND - INVESTOR CLASS
<MULTIPLIER> 1000
<S> <C>
<PERIOD-TYPE> YEAR
<FISCAL-YEAR-END> OCT-31-2000
<PERIOD-END> OCT-31-2000
<INVESTMENTS-AT-COST> 1,525,441
<INVESTMENTS-AT-VALUE> 2,019,173
<RECEIVABLES> 32,013
<ASSETS-OTHER> 0
<OTHER-ITEMS-ASSETS> 0
<TOTAL-ASSETS> 2,051,186
<PAYABLE-FOR-SECURITIES> 63,064
<SENIOR-LONG-TERM-DEBT> 0
<OTHER-ITEMS-LIABILITIES> 2,230
<TOTAL-LIABILITIES> 65,294
<SENIOR-EQUITY> 1,034
<PAID-IN-CAPITAL-COMMON> 1,116,470
<SHARES-COMMON-STOCK> 103,436
<SHARES-COMMON-PRIOR> 98,171
<ACCUMULATED-NII-CURRENT> (2,850)
<OVERDISTRIBUTION-NII> 0
<ACCUMULATED-NET-GAINS> 378,667
<OVERDISTRIBUTION-GAINS> 0
<ACCUM-APPREC-OR-DEPREC> 492,571
<NET-ASSETS> 1,985,892
<DIVIDEND-INCOME> 7,757
<INTEREST-INCOME> 5,836
<OTHER-INCOME> 0
<EXPENSES-NET> 16,422
<NET-INVESTMENT-INCOME> (2,829)
<REALIZED-GAINS-CURRENT> 378,972
<APPREC-INCREASE-CURRENT> 272,192
<NET-CHANGE-FROM-OPS> 648,335
<EQUALIZATION> 0
<DISTRIBUTIONS-OF-INCOME> (3,439)
<DISTRIBUTIONS-OF-GAINS> (114,651)
<DISTRIBUTIONS-OTHER> 0
<NUMBER-OF-SHARES-SOLD> 59,899
<NUMBER-OF-SHARES-REDEEMED> (41,522)
<SHARES-REINVESTED> 8,241
<NET-CHANGE-IN-ASSETS> 984,777
<ACCUMULATED-NII-PRIOR> 3,419
<ACCUMULATED-GAINS-PRIOR> 114,478
<OVERDISTRIB-NII-PRIOR> 0
<OVERDIST-NET-GAINS-PRIOR> 0
<GROSS-ADVISORY-FEES> 16,406
<INTEREST-EXPENSE> 0
<GROSS-EXPENSE> 16,422
<AVERAGE-NET-ASSETS> 1,633,625
<PER-SHARE-NAV-BEGIN> 13.02
<PER-SHARE-NII> (0.03)
<PER-SHARE-GAIN-APPREC> 7.63
<PER-SHARE-DIVIDEND> (0.04)
<PER-SHARE-DISTRIBUTIONS> (1.48)
<RETURNS-OF-CAPITAL> 0.00
<PER-SHARE-NAV-END> 19.10
<EXPENSE-RATIO> 1.00
</TABLE>
