<ARTICLE> 5 <CIK> 0000932064 <NAME> SECURITY DYNAMICS TECHNOLOGIES, INC. <MULTIPLIER> 1,000 <CURRENCY> US DOLLARS <PERIOD-TYPE> 6-MOS <FISCAL-YEAR-END> DEC-31-1997 <PERIOD-START> JAN-01-1997 <PERIOD-END> JUN-30-1997 <EXCHANGE-RATE> 1 <CASH> 21,828 <SECURITIES> 86,437 <RECEIVABLES> 17,941 <ALLOWANCES> 550 <INVENTORY> 3,189 <CURRENT-ASSETS> 134,986 <PP&E> 17,068 <DEPRECIATION> 4,749 <TOTAL-ASSETS> 151,600 <CURRENT-LIABILITIES> 16,493 <BONDS> 0 <PREFERRED-MANDATORY> 0 <PREFERRED> 0 <COMMON> 351 <OTHER-SE> 132,178 <TOTAL-LIABILITY-AND-EQUITY> 151,600<F2> <SALES> 56,097 <TOTAL-REVENUES> 56,097 <CGS> 12,241 <TOTAL-COSTS> 42,245 <OTHER-EXPENSES> 0 <LOSS-PROVISION> 90 <INTEREST-EXPENSE> 0 <INCOME-PRETAX> 16,321<F1> <INCOME-TAX> 6,090 <INCOME-CONTINUING> 10,231 <DISCONTINUED> 0 <EXTRAORDINARY> 0 <CHANGES> 0 <NET-INCOME> 10,231 <EPS-PRIMARY> 0.28 <EPS-DILUTED> 0.28 <FN> <F1>INCOME-PRETAX INCLUDES $2,649 INTEREST AND OTHER INCOME. <F2>TOTAL LIABILITY AND EQUITY INCLUDES $2,578 MINORITY INTEREST. </FN>