<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>