<TABLE> <S> <C>

<PAGE>
 
<ARTICLE> 5
<LEGEND>
THIS SCHEDULE CONTAINS SUMMARY FINANCIAL INFORMATION EXTRACTED FROM FORM 10-Q
PERIOD ENDED 6/30/98 AND IS QUALIFIED IN ITS ENTIRETY BY REFERENCE TO SUCH
FINANCIAL STATEMENTS.
</LEGEND>
<CIK> 0000895659
<NAME> DIAGNOSTIC HEALTH SERVICES, INC.
       
<S>                             <C>                     <C>
<PERIOD-TYPE>                   3-MOS                   6-MOS
<FISCAL-YEAR-END>                          DEC-31-1998             DEC-31-1998
<PERIOD-START>                             APR-01-1998             JAN-01-1998
<PERIOD-END>                               JUN-30-1998             JUN-30-1998
<CASH>                                               0               5,731,972
<SECURITIES>                                         0                       0
<RECEIVABLES>                                        0              15,281,970
<ALLOWANCES>                                         0                (403,039)
<INVENTORY>                                          0                       0
<CURRENT-ASSETS>                                     0              27,346,614
<PP&E>                                               0              45,087,396
<DEPRECIATION>                                       0             (10,214,699)
<TOTAL-ASSETS>                                       0             109,505,318
<CURRENT-LIABILITIES>                                0              11,047,722
<BONDS>                                              0              35,536,153
<PREFERRED-MANDATORY>                                0                     696
<PREFERRED>                                          0                       0
<COMMON>                                             0                  11,637
<OTHER-SE>                                           0              55,490,981
<TOTAL-LIABILITY-AND-EQUITY>                         0             109,505,318
<SALES>                                     15,153,993              29,568,383
<TOTAL-REVENUES>                            15,153,993              29,568,383
<CGS>                                                0                       0
<TOTAL-COSTS>                               17,060,368              28,209,912
<OTHER-EXPENSES>                               (39,159)                (92,292)
<LOSS-PROVISION>                               113,631                 257,775
<INTEREST-EXPENSE>                           1,160,868               2,175,206
<INCOME-PRETAX>                             (3,141,715)               (982,218)
<INCOME-TAX>                                (1,005,430)               (314,392)
<INCOME-CONTINUING>                         (2,136,285)               (667,826)
<DISCONTINUED>                                       0                       0
<EXTRAORDINARY>                                      0                       0
<CHANGES>                                            0                       0
<NET-INCOME>                                (2,136,285)               (667,826)
<EPS-PRIMARY>                                    (0.19)                  (0.06)
<EPS-DILUTED>                                    (0.19)                  (0.06)
        

</TABLE>