Fourteen patients with relapsing ovarian cancer were treated with Mitomycin C (Mit C) and 5 Fluorouracil (5-FU). All but one patient (one responder) were defined as platinum resistant. The drug dosaging was Mit C 10 mg/m2 IV day 1 every 6 weeks, and 5-FU 500 mg/m2 IV days 1-3, every 3 weeks. Therapy was evaluated clinically and with ultrasound every 6 weeks. Toxicity was graded using the Gynecologic Oncology Group adverse criteria. All patients had been previously treated with platinum containing chemotherapeutic regimens with a mean cumulative total dose of 418 mg/m2 and 1308 mg/m2 of cisplatin and carboplatin, respectively. The mean time interval from completion of the last platinum containing regimen to entry in this study was 3.6 months. There were 4 responders, 1 complete, and 3 partial. The duration of the responses were 13 weeks for the complete responder, and 6, 6, and 12 weeks for the partial responders. No factor was identified which was predictive for response. Grade 3/4 granulocytopenia and thrombocytopenia were experienced by 43% and 21% of all patients respectively. Despite our documented response rate of 29%, the short duration of responses and high incidence of severe and life threatening hematologic toxicity preclude this regimen from being of any significant benefit to relapsing platinum resistant ovarian cancer patients.