Cis-Dichlorodiammineplatinum(II) (cis-platinum) was used in the treatment of 25 patients with advanced ovarian adenocarcinoma refractory to alkylating agents. Seven of 24 evaluable patients (29%) responded to cis-platinum (one complete response and six partial responses). Life-table analysis of survival indicates that patients responding to therapy survive longer than those who fail to respond (9 months versus 3.2 months) (P = 0.014). In previously treated patients given 70 mg/m2 iv with forced diuresis, there was substantial nausea and vomiting (100%), hematologic toxicity (67%), and renal toxicity (34%). A review of the single-agent activity of cis-platinum in other ovarian cancer studies indicates an overall response rate of 25% (40 of 161 patients). At least nine combination chemotherapy studies utilizing cis-platinum are in progress, and preliminary information from several of these is encouraging and suggests that cis-platinum-containing combinations may have a major role in the treatment of ovarian adenocarcinoma.