A series of 105 patients with metastatic prostatic cancer, having progressed on first-line hormonal treatment, were randomised to high-dose medroxyprogesterone acetate (MPA) 1000 mg i.m. daily for 15 days, followed by 1000 mg weekly (53 patients), or to estramustine 280 mg per os twice daily (52 patients). The treatment was discontinued because of side effects in 3 of 51 evaluable MPA-treated patients and in 8 of 51 evaluable estramustine-treated patients. Progression-free survival was short in both groups and no statistically significant difference between them was observed. After 1 year, 70% of the patients had died and there was no statistically significant difference between the 2 treatments in the cumulative observed survival rates. According to modified SPCG criteria, remissions lasting from 12 to 56 weeks were noted in 13 MPA-treated patients and in 4 estramustine-treated patients. This difference was statistically significant. After cross-over, 6 of 33 patients in the MPA group had a remission compared with 1 of 24 in the estramustine group. It was concluded that the response rate, considering both subjective and objective response criteria, was better with MPA and the side effects were fewer.