WARNING: THE EDGAR SYSTEM ENCOUNTERED ERROR(S) WHILE PROCESSING THIS SCHEDULE.
<TABLE> <S> <C>
<ARTICLE> 6
<CIK> 0000872649
<NAME> LOOMIS SAYLES & COMPANY, L.P.
<SERIES>
<NUMBER> 131
<NAME> LOOMIS SAYLES INVESTMENT GRADE BOND FUND, INSTITUTIONAL
<S> <C>
<PERIOD-TYPE> 6-MOS
<FISCAL-YEAR-END> SEP-30-2000
<PERIOD-START> OCT-01-1999
<PERIOD-END> MAR-31-2000
<INVESTMENTS-AT-COST> 21857765
<INVESTMENTS-AT-VALUE> 21650913
<RECEIVABLES> 580986
<ASSETS-OTHER> 70705
<OTHER-ITEMS-ASSETS> 0
<TOTAL-ASSETS> 22302604
<PAYABLE-FOR-SECURITIES> 0
<SENIOR-LONG-TERM-DEBT> 0
<OTHER-ITEMS-LIABILITIES> 38302
<TOTAL-LIABILITIES> 38302
<SENIOR-EQUITY> 0
<PAID-IN-CAPITAL-COMMON> 22483001
<SHARES-COMMON-STOCK> 256269
<SHARES-COMMON-PRIOR> 243677
<ACCUMULATED-NII-CURRENT> 126597
<OVERDISTRIBUTION-NII> 0
<ACCUMULATED-NET-GAINS> 0
<OVERDISTRIBUTION-GAINS> (138359)
<ACCUM-APPREC-OR-DEPREC> (206937)
<NET-ASSETS> 22264302
<DIVIDEND-INCOME> 14761
<INTEREST-INCOME> 845103
<OTHER-INCOME> 0
<EXPENSES-NET> (123803)
<NET-INVESTMENT-INCOME> 736061
<REALIZED-GAINS-CURRENT> (42751)
<APPREC-INCREASE-CURRENT> 393344
<NET-CHANGE-FROM-OPS> 1086654
<EQUALIZATION> 0
<DISTRIBUTIONS-OF-INCOME> (88910)
<DISTRIBUTIONS-OF-GAINS> 0
<DISTRIBUTIONS-OTHER> 0
<NUMBER-OF-SHARES-SOLD> 41197
<NUMBER-OF-SHARES-REDEEMED> (34881)
<SHARES-REINVESTED> 6276
<NET-CHANGE-IN-ASSETS> 969241
<ACCUMULATED-NII-PRIOR> 114023
<ACCUMULATED-GAINS-PRIOR> 0
<OVERDISTRIB-NII-PRIOR> 0
<OVERDIST-NET-GAINS-PRIOR> (95608)
<GROSS-ADVISORY-FEES> 42974
<INTEREST-EXPENSE> 0
<GROSS-EXPENSE> 290678
<AVERAGE-NET-ASSETS> 2424705
<PER-SHARE-NAV-BEGIN> 9.96
<PER-SHARE-NII> 0.36
<PER-SHARE-GAIN-APPREC> 0.16
<PER-SHARE-DIVIDEND> (0.36)
<PER-SHARE-DISTRIBUTIONS> 0
<RETURNS-OF-CAPITAL> 0
<PER-SHARE-NAV-END> 10.12
<EXPENSE-RATIO> 0.55
[AVG-DEBT-OUTSTANDING] 0
[AVG-DEBT-PER-SHARE] 0
</TABLE>
