<ARTICLE> 5
<CIK> 0000779282
<NAME> DIANON SYSTEMS
<MULTIPLIER> 1,000
<CURRENCY> U.S. DOLLARS
       
                             
<PERIOD-TYPE>                   3-MOS
<FISCAL-YEAR-END>                          DEC-31-1998
<PERIOD-END>                               MAR-31-1998
<EXCHANGE-RATE>                                      1
<CASH>                                           9,971
<SECURITIES>                                         0
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<ALLOWANCES>                                     1,311
<INVENTORY>                                        718
<CURRENT-ASSETS>                                28,957
<PP&E>                                          12,710
<DEPRECIATION>                                   6,728
<TOTAL-ASSETS>                                  36,692
<CURRENT-LIABILITIES>                            6,388
<BONDS>                                              0
<PREFERRED-MANDATORY>                                0
<PREFERRED>                                          0
<COMMON>                                            68
<OTHER-SE>                                      30,124
<TOTAL-LIABILITY-AND-EQUITY>                    33,692
<SALES>                                         15,081
<TOTAL-REVENUES>                                15,081
<CGS>                                            8,459
<TOTAL-COSTS>                                    8,459
<OTHER-EXPENSES>                                 5,507
<LOSS-PROVISION>                                     0
<INTEREST-EXPENSE>                                  16
<INCOME-PRETAX>                                  1,298
<INCOME-TAX>                                       558
<INCOME-CONTINUING>                                740
<DISCONTINUED>                                       0
<EXTRAORDINARY>                                      0
<CHANGES>                                            0
<NET-INCOME>                                       740
<EPS-PRIMARY>                                     0.11
<EPS-DILUTED>                                     0.11