<ARTICLE> 5 <CIK> 0001022079 <NAME> QUEST DIAGNOSTICS INCORPORATED <MULTIPLIER> 1000 <CURRENCY> US <PERIOD-TYPE> 3-MOS <FISCAL-YEAR-END> DEC-31-1999 <PERIOD-START> JAN-01-1999 <PERIOD-END> MAR-31-1999 <EXCHANGE-RATE> 1 <CASH> 154,197 <SECURITIES> 0 <RECEIVABLES> 229,786 <ALLOWANCES> 70,408 <INVENTORY> 33,042 <CURRENT-ASSETS> 530,639 <PP&E> 241,295 <DEPRECIATION> 355,084 <TOTAL-ASSETS> 1,318,199 <CURRENT-LIABILITIES> 309,205 <BONDS> 0 <PREFERRED-MANDATORY> 0 <PREFERRED> 1,000 <COMMON> 1,197,579 <OTHER-SE> (621,292) <TOTAL-LIABILITY-AND-EQUITY> 1,318,199 <SALES> 381,841 <TOTAL-REVENUES> 381,841 <CGS> 226,995 <TOTAL-COSTS> 354,008 <OTHER-EXPENSES> 1,302 <LOSS-PROVISION> 20,337 <INTEREST-EXPENSE> 7,359 <INCOME-PRETAX> 14,078 <INCOME-TAX> 6,645 <INCOME-CONTINUING> 7,433 <DISCONTINUED> 0 <EXTRAORDINARY> 0 <CHANGES> 0 <NET-INCOME> 7,433 <EPS-PRIMARY> 0.25 <EPS-DILUTED> 0.24