Thirty-four patients with advanced or recurrent mixed mesodermal sarcoma of the uterus were entered in a study of single-agent cisplatin as second-line chemotherapy at a dose of 50 mg/m2 iv every 3 weeks. Twenty-eight of the 34 patients had mixed mesodermal sarcomas and measurable disease and had received one or more courses of the drug. Of these patients, five (18%) had objective response to therapy. Two patients who developed clinical complete response had long progression-free intervals (14 and 16 months) and remained alive at 21 and 36 months after initiation of therapy. Adverse effects were those described in a number of series employing cisplatin and were tolerable. Cisplatin thus appears to have definite activity as a second-line agent in the treatment of mixed mesodermal sarcomas of the uterus.