<ARTICLE> 5
<CIK> 0001022079
<NAME> QUEST DIAGNOSTICS INCORPORATED
<MULTIPLIER> 1,000
<CURRENCY>U.S. DOLLAR

                                                  
<PERIOD-TYPE>                   9-MOS                   9-MOS
<FISCAL-YEAR-END>                          DEC-31-2000             DEC-31-1999
<PERIOD-START>                             JAN-01-2000             JAN-01-1999
<PERIOD-END>                               SEP-30-2000             SEP-30-1999
<EXCHANGE-RATE>                                      1                       1
<CASH>                                         161,786                  36,799
<SECURITIES>                                         0                       0
<RECEIVABLES>                                  651,346                 640,575
<ALLOWANCES>                                   137,955                  86,891
<INVENTORY>                                     43,012                  51,376
<CURRENT-ASSETS>                             1,049,348                 875,011
<PP&E>                                         424,081                 445,000
<DEPRECIATION>                                 426,134                 358,786
<TOTAL-ASSETS>                               3,006,154               2,826,565
<CURRENT-LIABILITIES>                          987,176                 638,810
<BONDS>                                              0                       0
<PREFERRED-MANDATORY>                            1,000                   1,000
<PREFERRED>                                          0                       0
<COMMON>                                     1,575,686               1,468,001
<OTHER-SE>                                   (590,049)               (612,984)
<TOTAL-LIABILITY-AND-EQUITY>                 3,006,154               2,826,565
<SALES>                                              0                       0
<TOTAL-REVENUES>                             2,584,828               1,390,717
<CGS>                                        1,554,216                 859,569
<TOTAL-COSTS>                                2,308,116               1,273,408
<OTHER-EXPENSES>                                 4,474                  34,766
<LOSS-PROVISION>                               181,646                  81,775
<INTEREST-EXPENSE>                              89,430                  31,392
<INCOME-PRETAX>                                147,428                  33,026
<INCOME-TAX>                                    70,739                  19,763
<INCOME-CONTINUING>                             76,689                  13,263
<DISCONTINUED>                                       0                       0
<EXTRAORDINARY>                                      0                 (2,139)
<CHANGES>                                            0                       0
<NET-INCOME>                                    76,689                  11,124
<EPS-BASIC>                                       1.72                    0.34
<EPS-DILUTED>                                     1.64                    0.34

<F1>During the fourth quarter of 1999, the Company reclassified certain expense
items, primarily related to a portion of occupancy costs and professional
liability insurance expense items, from selling, general and administrative
expenses to cost of services, to better reflect the cost of performing testing.