<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> 001
<NAME> Merrimac Cash Series Premium Class
<S> <C>
<PERIOD-TYPE> 6-MOS
<FISCAL-YEAR-END> DEC-31-2000
<PERIOD-END> JUN-30-2000
<INVESTMENTS-AT-COST> 318,363,372
<INVESTMENTS-AT-VALUE> 318,363,372
<RECEIVABLES> 0
<ASSETS-OTHER> 7,116
<OTHER-ITEMS-ASSETS> 8,531
<TOTAL-ASSETS> 318,379,019
<PAYABLE-FOR-SECURITIES> 0
<SENIOR-LONG-TERM-DEBT> 0
<OTHER-ITEMS-LIABILITIES> 2,280,413
<TOTAL-LIABILITIES> 2,280,413
<SENIOR-EQUITY> 0
<PAID-IN-CAPITAL-COMMON> 316,140,589
<SHARES-COMMON-STOCK> 29,499,510
<SHARES-COMMON-PRIOR> 0
<ACCUMULATED-NII-CURRENT> 0
<OVERDISTRIBUTION-NII> 0
<ACCUMULATED-NET-GAINS> (3,917)
<OVERDISTRIBUTION-GAINS> 0
<ACCUM-APPREC-OR-DEPREC> 0
<NET-ASSETS> 29,495,593
<DIVIDEND-INCOME> 0
<INTEREST-INCOME> 2,677,062
<OTHER-INCOME> 0
<EXPENSES-NET> 92,052
<NET-INVESTMENT-INCOME> 2,585,010
<REALIZED-GAINS-CURRENT> (4,530)
<APPREC-INCREASE-CURRENT> 0
<NET-CHANGE-FROM-OPS> 2,580,480
<EQUALIZATION> 0
<DISTRIBUTIONS-OF-INCOME> 2,585,010
<DISTRIBUTIONS-OF-GAINS> 0
<DISTRIBUTIONS-OTHER> 0
<NUMBER-OF-SHARES-SOLD> 461,530,803
<NUMBER-OF-SHARES-REDEEMED> 440,593,556
<SHARES-REINVESTED> 1,327,115
<NET-CHANGE-IN-ASSETS> 22,264,362
<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> 740,532
<AVERAGE-NET-ASSETS> 82,867,017
<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> 0.22
</TABLE>
