Iproplatin (cis-dichloro-trans dihydroxy-bis-isopropyl-amine platinum [IV]; CHIP) was administered intravenously (IV) at monthly intervals at doses of 300 mg/m2 and 240 mg/m2 to ten previously untreated and 97 previously treated patients with advanced ovarian carcinoma. The overall response rate was 78% among patients with no prior chemotherapy, 42% among patients with prior chemotherapy not including cisplatin, and 22% among patients with prior chemotherapy including cisplatin. Overall response rates to iproplatin were 6.4% and 54% in patients with/without clinical evidence of tumor resistance to cisplatin. Thrombocytopenia was the dose-limiting toxicity, median time to nadir and to recovery being 2 and 4 weeks, respectively. Patients who had received prior chemotherapy regimens for greater than 1 year showed a 10% greater reduction in platelet count (mean platelet nadir +/- SD, 57.5 +/- 49.96 X 10(3)/microL) and a higher incidence of grade 3 to 4 thrombocytopenia after the first cycle than patients who had received prior chemotherapy regimens for less than 1 year (94.7 +/- 65.99 X 10(3)/microL) Moderate to severe vomiting and diarrhea occurred in 84% and 16% of patients pretreated with chemotherapy. Neuropathy (6%) was reported only in patients with prior cisplatin treatment. Mild and reversible renal toxicity was observed in 6% of cases. Iproplatin is an active drug in ovarian cancer; the results achieved in patients previously treated with cisplatin strongly suggest that the two drugs are cross-resistant.