<TABLE> <S> <C>

<ARTICLE> 6
<SERIES>
   <NUMBER> 001
   <NAME> PIONEER TAX-FREE INCOME FUND CLASS A
       
<S>                             <C>
<PERIOD-TYPE>                   YEAR
<FISCAL-YEAR-END>                          DEC-31-1997
<PERIOD-END>                               DEC-31-1997
<INVESTMENTS-AT-COST>                        381644739
<INVESTMENTS-AT-VALUE>                       415025754
<RECEIVABLES>                                  7163304
<ASSETS-OTHER>                                   46011
<OTHER-ITEMS-ASSETS>                                 0
<TOTAL-ASSETS>                               422235069
<PAYABLE-FOR-SECURITIES>                             0
<SENIOR-LONG-TERM-DEBT>                              0
<OTHER-ITEMS-LIABILITIES>                      1147857
<TOTAL-LIABILITIES>                            1147857
<SENIOR-EQUITY>                                      0
<PAID-IN-CAPITAL-COMMON>                     387708414
<SHARES-COMMON-STOCK>                         34002418
<SHARES-COMMON-PRIOR>                         36947391
<ACCUMULATED-NII-CURRENT>                            0
<OVERDISTRIBUTION-NII>                            2127
<ACCUMULATED-NET-GAINS>                              0
<OVERDISTRIBUTION-GAINS>                             0
<ACCUM-APPREC-OR-DEPREC>                     333810150
<NET-ASSETS>                                 421087212
<DIVIDEND-INCOME>                                    0
<INTEREST-INCOME>                             24819037
<OTHER-INCOME>                                       0
<EXPENSES-NET>                                 3950625
<NET-INVESTMENT-INCOME>                       20868412
<REALIZED-GAINS-CURRENT>                       5728646
<APPREC-INCREASE-CURRENT>                      9973302
<NET-CHANGE-FROM-OPS>                         36570360
<EQUALIZATION>                                       0
<DISTRIBUTIONS-OF-INCOME>                     20562056
<DISTRIBUTIONS-OF-GAINS>                       8029783
<DISTRIBUTIONS-OTHER>                                0
<NUMBER-OF-SHARES-SOLD>                        2922958
<NUMBER-OF-SHARES-REDEEMED>                    7521806
<SHARES-REINVESTED>                            1653875
<NET-CHANGE-IN-ASSETS>                      (25820262)
<ACCUMULATED-NII-PRIOR>                              0
<ACCUMULATED-GAINS-PRIOR>                      2265920
<OVERDISTRIB-NII-PRIOR>                              0
<OVERDIST-NET-GAINS-PRIOR>                           0
<GROSS-ADVISORY-FEES>                          2063785
<INTEREST-EXPENSE>                                   0
<GROSS-EXPENSE>                                4032892
<AVERAGE-NET-ASSETS>                         421478988       
<PER-SHARE-NAV-BEGIN>                            11.96
<PER-SHARE-NII>                                    .59
<PER-SHARE-GAIN-APPREC>                            .45
<PER-SHARE-DIVIDEND>                               .59
<PER-SHARE-DISTRIBUTIONS>                          .24
<RETURNS-OF-CAPITAL>                                 0
<PER-SHARE-NAV-END>                              12.17
<EXPENSE-RATIO>                                    .93
<AVG-DEBT-OUTSTANDING>                               0
<AVG-DEBT-PER-SHARE>                                 0
        

        

</TABLE>