<ARTICLE> 5 <LEGEND> </LEGEND> <CIK> 0000779282 <NAME> Dianon Systems, Inc. <MULTIPLIER> 1,000 <CURRENCY> U.S. Dollars <PERIOD-TYPE> 9-MOS <FISCAL-YEAR-END> DEC-31-2000 <PERIOD-START> JAN-01-2000 <PERIOD-END> SEP-30-2000 <EXCHANGE-RATE> 1 <CASH> 12,285 <SECURITIES> 0 <RECEIVABLES> 22,890 <ALLOWANCES> 1,287 <INVENTORY> 1,344 <CURRENT-ASSETS> 36,886 <PP&E> 19,528 <DEPRECIATION> 13,782 <TOTAL-ASSETS> 56,909 <CURRENT-LIABILITIES> 7,493 <BONDS> 0 <PREFERRED-MANDATORY> 0 <PREFERRED> 0 <COMMON> 73 <OTHER-SE> 44,975 <TOTAL-LIABILITY-AND-EQUITY> 56,909 <SALES> 70,099 <TOTAL-REVENUES> 70,099 <CGS> 39,923 <TOTAL-COSTS> 39,923 <OTHER-EXPENSES> 22,643 <LOSS-PROVISION> 0 <INTEREST-EXPENSE> 293 <INCOME-PRETAX> 7,763 <INCOME-TAX> 3,144 <INCOME-CONTINUING> 4,619 <DISCONTINUED> 0 <EXTRAORDINARY> 0 <CHANGES> 0 <NET-INCOME> 4,619 <EPS-BASIC> 0.65 <EPS-DILUTED> 0.59