<ARTICLE> 5 <CIK> 0001022079 <NAME> QUEST DIAGNOSTICS INCORPORATED <MULTIPLIER> 1,000 <PERIOD-TYPE> 6-MOS <FISCAL-YEAR-END> DEC-31-1999 <PERIOD-START> JAN-01-1999 <PERIOD-END> JUN-30-1999 <CASH> 148,478 <SECURITIES> 0 <RECEIVABLES> 224,920 <ALLOWANCES> 68,766 <INVENTORY> 32,923 <CURRENT-ASSETS> 527,807 <PP&E> 243,107 <DEPRECIATION> 355,377 <TOTAL-ASSETS> 1,312,807 <CURRENT-LIABILITIES> 313,355 <BONDS> 0 <PREFERRED-MANDATORY> 0 <PREFERRED> 1,000 <COMMON> 1,202,187 <OTHER-SE> (605,369) <TOTAL-LIABILITY-AND-EQUITY> 1,312,807 <SALES> 775,875 <TOTAL-REVENUES> 775,875 <CGS> 452,654 <TOTAL-COSTS> 711,309 <OTHER-EXPENSES> 3,301 <LOSS-PROVISION> 40,242 <INTEREST-EXPENSE> 12,367 <INCOME-PRETAX> 38,585 <INCOME-TAX> 18,065 <INCOME-CONTINUING> 20,520 <DISCONTINUED> 0 <EXTRAORDINARY> 0 <CHANGES> 0 <NET-INCOME> 20,520 <EPS-BASIC> 0.69 <EPS-DILUTED> 0.67