The aim of this phase II trial was to examine the efficacy of a new nitrosourea, cystemustine, in soft tissue sarcoma. Between January 1990 and March 1991, 32 pretreated patients with advanced soft tissue sarcoma were enrolled. Cystemustine was given every 2 weeks at 60 mg/m2 via a 15-min i.v. infusion. All eligible patients were considered evaluable for response and toxicity (WHO criteria). Of the 32 enrolled patients, 4 were ineligible, leaving 28 evaluable patients. All but 1 had been pretreated: 6 with adjuvant chemotherapy, 18 patients with first-line palliative chemotherapy without nitrosourea, 3 with both treatments, and 18 had received radiotherapy. Median age was 54 years (range 20-73) and median performance status was 1 (0-2). One partial response (PR, duration 12 weeks), 2 stable disease and 25 progressions were observed, giving an overall response rate of 3.57% (confidence interval: 0.1-18.4%). Toxicity was mild, and was mainly neutropenia (no grade 3 or 4), thrombocytopenia (3.57% grade 3 and grade 4) and nausea-vomiting (no grade 3 or 4). It should be noted that the treatment for the patient who obtained a PR was third line with no previous response. Cystemustine with this schedule appears to have a low clinical activity and toxicity in advanced soft tissue sarcoma.