<TABLE> <S> <C>

<PAGE>
 
<ARTICLE> 5
<LEGEND>
THIS SCHEDULE CONTAINS SUMMARY FINANCIAL INFORMATION EXTRACTED FROM FORM 10-K
PERIOD ENDING 12/31/98 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>                   YEAR                   YEAR
<FISCAL-YEAR-END>                          DEC-31-1998             DEC-31-1997
<PERIOD-START>                             JAN-01-1998             JAN-01-1997
<PERIOD-END>                               DEC-31-1998             DEC-31-1997
<CASH>                                       1,087,349               5,126,114
<SECURITIES>                                         0                       0
<RECEIVABLES>                               11,613,352              18,699,934
<ALLOWANCES>                                 1,428,636               (612,437)
<INVENTORY>                                          0                       0
<CURRENT-ASSETS>                            13,713,674              26,997,683
<PP&E>                                      36,341,393              37,576,561
<DEPRECIATION>                            (12,131,560)             (8,876,887)
<TOTAL-ASSETS>                              67,866,655             107,854,175
<CURRENT-LIABILITIES>                       11,079,503              17,776,436
<BONDS>                                     37,842,635              35,310,066
<PREFERRED-MANDATORY>                              747                     696
<PREFERRED>                                          0                       0
<COMMON>                                        11,714                  10,719
<OTHER-SE>                                  15,068,812              49,941,248
<TOTAL-LIABILITY-AND-EQUITY>                67,866,655             107,854,175
<SALES>                                     44,844,442              52,920,804
<TOTAL-REVENUES>                            44,844,442              52,920,804
<CGS>                                                0                       0
<TOTAL-COSTS>                               76,095,046              40,367,490
<OTHER-EXPENSES>                              (83,778)               (369,403)
<LOSS-PROVISION>                             1,913,004                 890,161
<INTEREST-EXPENSE>                           4,341,991               4,056,301
<INCOME-PRETAX>                           (37,421,821)               7,976,255
<INCOME-TAX>                               (6,972,618)               2,215,726
<INCOME-CONTINUING>                       (30,449,203)               5,760,529
<DISCONTINUED>                                       0               (326,934)
<EXTRAORDINARY>                                      0                       0
<CHANGES>                                 (10,833,156)                       0
<NET-INCOME>                              (41,282,359)               5,433,595
<EPS-PRIMARY>                                   (3.67)                    0.57
<EPS-DILUTED>                                   (3.73)                    0.48<F1>
<FN>
<F1>TOTAL COSTS FOR THE YEAR-END 12/31/98 INCLUDES NON-RECURRING CHARGES OF
$6,596,683 FOR RESTRUCTURING EXPENSES AND $24,672,291 FOR IMPAIRMENT ON
ACQUIRED ASSETS.
</FN>
        

</TABLE>