Twenty-nine patients with recurrent advanced stage ovarian cancer were treated with 5-fluorouracil (5-FU) and leucovorin by intravenous bolus on 5 consecutive days, repeated every 3 weeks. Twenty-one of these patients had experienced disease progression while receiving a cisplatin- or carboplatin-based regimen. There were 2 clinical complete responders and 1 partial responder to therapy (10% response rate; 95% confidence interval, 2 to 27%) and 11 individuals who experienced stable disease for periods ranging from 5 to 27 months. Of 204 cycles of therapy administered, 9 cycles were associated with hospitalization. These occurred in the more heavily pretreated members of the cohort. 5-FU and leucovorin appear to have activity in platinum-refractory ovarian cancer and form a well-tolerated regimen in most patients.