<TABLE> <S> <C>
<ARTICLE> 6
<CIK> 0000741375
<NAME> MAS FUNDS
<SERIES>
<NUMBER> 312
<NAME> MID CAP VALUE PORTFOLIO, INVESTMENT CLASS
<MULTIPLIER> 1,000
<S> <C>
<PERIOD-TYPE> 12-MOS
<FISCAL-YEAR-END> SEP-30-2000
<PERIOD-START> OCT-01-1999
<PERIOD-END> SEP-30-2000
<INVESTMENTS-AT-COST> 1,415,243
<INVESTMENTS-AT-VALUE> 1,517,289
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<OTHER-ITEMS-ASSETS> 1
<TOTAL-ASSETS> 1,528,139
<PAYABLE-FOR-SECURITIES> 22,444
<SENIOR-LONG-TERM-DEBT> 0
<OTHER-ITEMS-LIABILITIES> 3,239
<TOTAL-LIABILITIES> 25,683
<SENIOR-EQUITY> 0
<PAID-IN-CAPITAL-COMMON> 1,234,906
<SHARES-COMMON-STOCK> 1,185
<SHARES-COMMON-PRIOR> 1,156
<ACCUMULATED-NII-CURRENT> 3,073
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<OVERDISTRIBUTION-GAINS> 0
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<NET-ASSETS> 1,502,456
<DIVIDEND-INCOME> 7,421
<INTEREST-INCOME> 5,918
<OTHER-INCOME> 0
<EXPENSES-NET> (10,242)
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<REALIZED-GAINS-CURRENT> 167,559
<APPREC-INCREASE-CURRENT> 118,977
<NET-CHANGE-FROM-OPS> 289,633
<EQUALIZATION> 0
<DISTRIBUTIONS-OF-INCOME> (37)
<DISTRIBUTIONS-OF-GAINS> (2,499)
<DISTRIBUTIONS-OTHER> 0
<NUMBER-OF-SHARES-SOLD> 747
<NUMBER-OF-SHARES-REDEEMED> (822)
<SHARES-REINVESTED> 104
<NET-CHANGE-IN-ASSETS> 715,608
<ACCUMULATED-NII-PRIOR> 3,056
<ACCUMULATED-GAINS-PRIOR> 100,654
<OVERDISTRIB-NII-PRIOR> 0
<OVERDIST-NET-GAINS-PRIOR> 0
<GROSS-ADVISORY-FEES> 8,821
<INTEREST-EXPENSE> 0
<GROSS-EXPENSE> 10,413
<AVERAGE-NET-ASSETS> 1,175,916
<PER-SHARE-NAV-BEGIN> 21.80
<PER-SHARE-NII> 0.03
<PER-SHARE-GAIN-APPREC> 5.75
<PER-SHARE-DIVIDEND> (0.04)
<PER-SHARE-DISTRIBUTIONS> (2.57)
<RETURNS-OF-CAPITAL> 0
<PER-SHARE-NAV-END> 24.97
<EXPENSE-RATIO> 1.02
</TABLE>
