<TABLE> <S> <C>
<ARTICLE> 6
<LEGEND>
This schedule contains summary financial information
extracted from Merrimac Series,
form N-SAR for the period ended June 30, 2000
and is qualified in its entirety by reference to
such financial statements.
</LEGEND>
<SERIES>
<NUMBER> 005
<NAME> Merrimac Treasury Series Institutional Cla
<S> <C>
<PERIOD-TYPE> 6-MOS
<FISCAL-YEAR-END> DEC-31-2000
<PERIOD-END> JUN-30-2000
<INVESTMENTS-AT-COST> 214,254,098
<INVESTMENTS-AT-VALUE> 214,254,098
<RECEIVABLES> 0
<ASSETS-OTHER> 11,413
<OTHER-ITEMS-ASSETS> 6,380
<TOTAL-ASSETS> 214,271,891
<PAYABLE-FOR-SECURITIES> 0
<SENIOR-LONG-TERM-DEBT> 0
<OTHER-ITEMS-LIABILITIES> 1,271,978
<TOTAL-LIABILITIES> 1,271,978
<SENIOR-EQUITY> 0
<PAID-IN-CAPITAL-COMMON> 212,995,137
<SHARES-COMMON-STOCK> 180,668,194
<SHARES-COMMON-PRIOR> 0
<ACCUMULATED-NII-CURRENT> 0
<OVERDISTRIBUTION-NII> 0
<ACCUMULATED-NET-GAINS> 6,714
<OVERDISTRIBUTION-GAINS> 0
<ACCUM-APPREC-OR-DEPREC> 0
<NET-ASSETS> 180,674,908
<DIVIDEND-INCOME> 0
<INTEREST-INCOME> 6,167,949
<OTHER-INCOME> 0
<EXPENSES-NET> 545,731
<NET-INVESTMENT-INCOME> 5,622,218
<REALIZED-GAINS-CURRENT> 6,148
<APPREC-INCREASE-CURRENT> 0
<NET-CHANGE-FROM-OPS> 5,628,366
<EQUALIZATION> 0
<DISTRIBUTIONS-OF-INCOME> 5,622,218
<DISTRIBUTIONS-OF-GAINS> 0
<DISTRIBUTIONS-OTHER> 0
<NUMBER-OF-SHARES-SOLD> 375,605,235
<NUMBER-OF-SHARES-REDEEMED> 348,649,340
<SHARES-REINVESTED> 0
<NET-CHANGE-IN-ASSETS> 26,955,895
<ACCUMULATED-NII-PRIOR> 0
<ACCUMULATED-GAINS-PRIOR> 0
<OVERDISTRIB-NII-PRIOR> 0
<OVERDIST-NET-GAINS-PRIOR> 0
<GROSS-ADVISORY-FEES> 0
<INTEREST-EXPENSE> 0
<GROSS-EXPENSE> 582,671
<AVERAGE-NET-ASSETS> 220,073,347
<PER-SHARE-NAV-BEGIN> 1.00
<PER-SHARE-NII> 0.03
<PER-SHARE-GAIN-APPREC> 0.00
<PER-SHARE-DIVIDEND> (0.03)
<PER-SHARE-DISTRIBUTIONS> 0.00
<RETURNS-OF-CAPITAL> 0
<PER-SHARE-NAV-END> 1.00
<EXPENSE-RATIO> 0.50
</TABLE>
