A double-blind cross-over study was performed on 21 patients treated for endometrial carcinomas who had severe menopausal symptoms. The patients were randomized into two groups and received medroxyprogesterone acetate (MPA) 100 mg twice daily per os for 12 weeks and a placebo for 12 weeks. A significantly better effect on hot flushes and sweating was obtained with MPA than with the placebo. On average the maximum effect was achieved by MPA after 4-6 weeks. Six patients had a weight gain of more than 3 kg during the MPA administration, compared with none during the placebo administration. No significant difference was found in the blood pressure increase above 160/90 mmHg between MPA and placebo groups. Patients with endometrial carcinoma may risk exacerbation of their disease by undergoing therapy with exogenous estrogen. In contrast, MPA has been found of value in the treatment of disseminated endometrial carcinomas. In this study oral MPA was effective in the treatment of vasomotor menopausal symptoms and may be an alternative in women for whom estrogens might be hazardous.