<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> 011
<NAME> Merrimac Treasury Plus Series Institutiona
<S> <C>
<PERIOD-TYPE> 6-MOS
<FISCAL-YEAR-END> DEC-31-2000
<PERIOD-END> JUN-30-2000
<INVESTMENTS-AT-COST> 224,703,906
<INVESTMENTS-AT-VALUE> 224,703,906
<RECEIVABLES> 0
<ASSETS-OTHER> 0
<OTHER-ITEMS-ASSETS> 12,768
<TOTAL-ASSETS> 224,716,674
<PAYABLE-FOR-SECURITIES> 0
<SENIOR-LONG-TERM-DEBT> 0
<OTHER-ITEMS-LIABILITIES> 1,415,414
<TOTAL-LIABILITIES> 1,415,414
<SENIOR-EQUITY> 0
<PAID-IN-CAPITAL-COMMON> 223,301,326
<SHARES-COMMON-STOCK> 214,558,491
<SHARES-COMMON-PRIOR> 0
<ACCUMULATED-NII-CURRENT> 0
<OVERDISTRIBUTION-NII> 0
<ACCUMULATED-NET-GAINS> (66)
<OVERDISTRIBUTION-GAINS> 0
<ACCUM-APPREC-OR-DEPREC> 0
<NET-ASSETS> 214,558,425
<DIVIDEND-INCOME> 0
<INTEREST-INCOME> 6,862,966
<OTHER-INCOME> 0
<EXPENSES-NET> 571,982
<NET-INVESTMENT-INCOME> 6,290,984
<REALIZED-GAINS-CURRENT> 0
<APPREC-INCREASE-CURRENT> 0
<NET-CHANGE-FROM-OPS> 6,290,984
<EQUALIZATION> 0
<DISTRIBUTIONS-OF-INCOME> 6,290,984
<DISTRIBUTIONS-OF-GAINS> 0
<DISTRIBUTIONS-OTHER> 0
<NUMBER-OF-SHARES-SOLD> 575,043,959
<NUMBER-OF-SHARES-REDEEMED> 642,102,988
<SHARES-REINVESTED> 4,751
<NET-CHANGE-IN-ASSETS> (67,054,278)
<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> 572,905
<AVERAGE-NET-ASSETS> 233,449,611
<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> 0.49
</TABLE>
