<TABLE> <S> <C>

<ARTICLE> 6
<CIK> 0000078713
<NAME> PIONEER FUND
<SERIES>
   <NUMBER> 001
   <NAME> PIONEER FUND CLASS A
<CURRENCY> US

<S>                             <C>
<PERIOD-TYPE>                   6-MOS
<FISCAL-YEAR-END>                          DEC-31-2000
<PERIOD-END>                               JUN-30-2000
<EXCHANGE-RATE>                                      1
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<INVESTMENTS-AT-VALUE>                      7759059680
<RECEIVABLES>                                 33587686
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<OTHER-ITEMS-ASSETS>                               293
<TOTAL-ASSETS>                              7793070725
<PAYABLE-FOR-SECURITIES>                      14208693
<SENIOR-LONG-TERM-DEBT>                              0
<OTHER-ITEMS-LIABILITIES>                     16499056
<TOTAL-LIABILITIES>                           30707749
<SENIOR-EQUITY>                                      0
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<SHARES-COMMON-STOCK>                        139719111
<SHARES-COMMON-PRIOR>                        139466472
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<APPREC-INCREASE-CURRENT>                  (215080558)
<NET-CHANGE-FROM-OPS>                        280632618
<EQUALIZATION>                                       0
<DISTRIBUTIONS-OF-INCOME>                     10849179
<DISTRIBUTIONS-OF-GAINS>                             0
<DISTRIBUTIONS-OTHER>                                0
<NUMBER-OF-SHARES-SOLD>                       12661604
<NUMBER-OF-SHARES-REDEEMED>                   12609738
<SHARES-REINVESTED>                             200773
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<ACCUMULATED-NII-PRIOR>                              0
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<GROSS-EXPENSE>                               44700992
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<PER-SHARE-NAV-BEGIN>                            47.60
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<PER-SHARE-DISTRIBUTIONS>                            0
<RETURNS-OF-CAPITAL>                                 0
<PER-SHARE-NAV-END>                              49.34
<EXPENSE-RATIO>                                   1.12


</TABLE>