The present retrospective study assessed the prognostic value of serum CA125 assay at relapse in 73 patients with recurrent epithelial ovarian cancer. At the time of relapse, serum CA125 levels ranged from 7 to 7000 U ml-1. The 25%, 50% and 75% quantiles of CA125 levels were 76, 178 and 339 U ml-1, respectively. Antigen values were >35 U ml-1 in 67 (91.8%) of the 73 patients. Median time to recurrence was 16 months (range, 4-62 months). Serum CA125 levels at relapse were not related to site of recurrence, time to recurrence, FIGO stage, histologic type, tumor grade and residual disease after initial surgery. Sixty patients received salvage chemotherapy at relapse. In these patients survival after recurrence was significantly related to time to recurrence (< or = 6 months vs < 6 months, P = 0.0371; < or =12 months vs >12 months, P = 0.0014; < or =16 months vs >16 months, P = 0.0001), but not to CA125 level at relapse (at any cut-off value for the antigen: 35, 76, 178 and 339 U ml-1), site of recurrence, FIGO stage, histologic type, tumor grade and residual disease after initial surgery. In conclusion, time to recurrence was the only variable predictive of further survival in patients undergoing salvage chemotherapy for recurrent ovarian cancer, whereas serum CA125 level at relapse had no prognostic relevance.