<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> 121
<NAME> BALANCED FUND - INVESTOR CLASS
<MULTIPLIER> 1000
<S> <C>
<PERIOD-TYPE> YEAR
<FISCAL-YEAR-END> OCT-31-2000
<PERIOD-END> OCT-31-2000
<INVESTMENTS-AT-COST> 763,379
<INVESTMENTS-AT-VALUE> 859,047
<RECEIVABLES> 28,143
<ASSETS-OTHER> 0
<OTHER-ITEMS-ASSETS> 0
<TOTAL-ASSETS> 887,190
<PAYABLE-FOR-SECURITIES> 10,315
<SENIOR-LONG-TERM-DEBT> 0
<OTHER-ITEMS-LIABILITIES> 1,199
<TOTAL-LIABILITIES> 11,514
<SENIOR-EQUITY> 491
<PAID-IN-CAPITAL-COMMON> 749,611
<SHARES-COMMON-STOCK> 49,125
<SHARES-COMMON-PRIOR> 52,463
<ACCUMULATED-NII-CURRENT> 1,975
<OVERDISTRIBUTION-NII> 0
<ACCUMULATED-NET-GAINS> 28,190
<OVERDISTRIBUTION-GAINS> 0
<ACCUM-APPREC-OR-DEPREC> 95,409
<NET-ASSETS> 875,676
<DIVIDEND-INCOME> 5,520
<INTEREST-INCOME> 25,277
<OTHER-INCOME> 0
<EXPENSES-NET> 8,944
<NET-INVESTMENT-INCOME> 21,853
<REALIZED-GAINS-CURRENT> 31,415
<APPREC-INCREASE-CURRENT> (281)
<NET-CHANGE-FROM-OPS> 52,987
<EQUALIZATION> 0
<DISTRIBUTIONS-OF-INCOME> (21,560)
<DISTRIBUTIONS-OF-GAINS> (121,972)
<DISTRIBUTIONS-OTHER> 0
<NUMBER-OF-SHARES-SOLD> 12,079
<NUMBER-OF-SHARES-REDEEMED> (19,568)
<SHARES-REINVESTED> 8,364
<NET-CHANGE-IN-ASSETS> (49,644)
<ACCUMULATED-NII-PRIOR> 2,226
<ACCUMULATED-GAINS-PRIOR> 0
<OVERDISTRIB-NII-PRIOR> 120,193
<OVERDIST-NET-GAINS-PRIOR> 0
<GROSS-ADVISORY-FEES> 8,873
<INTEREST-EXPENSE> 0
<GROSS-EXPENSE> 8,944
<AVERAGE-NET-ASSETS> 891,189
<PER-SHARE-NAV-BEGIN> 18.95
<PER-SHARE-NII> 0.42
<PER-SHARE-GAIN-APPREC> 0.61
<PER-SHARE-DIVIDEND> (0.43)
<PER-SHARE-DISTRIBUTIONS> (2.54)
<RETURNS-OF-CAPITAL> 0.00
<PER-SHARE-NAV-END> 17.01
<EXPENSE-RATIO> 0.98
</TABLE>
