Forty-six patients with premenopausal or postmenopausal bleeding anomalies were given gestagen therapy for endometrial hyperplasia. The therapy was carried out using medroxyprogesterone acetate (MPA) or norethisterone acetate (NEA), in each case 10 mg/day either continuously or for 10 days per cycle. Therapy was controlled either by fractionated curettage or hysterectomy or on the basis of the subsequent clinical course. In the literature a regression of the endometrial hyperplasias in most cases under gestagen therapy has been described, and no case of development of carcinoma following therapy has been reported. These facts were confirmed in the patients treated with MPA, while among the women treated with NEA there were carcinomatous changes in three cases and progressive histologic control findings in three others. A pathologist asked to give a second opinion confirmed the diagnosis of carcinoma in one patient, but classified the histologic changes in the other two not as carcinomatous, but as adenomatous hyperplasia. The patient with confirmed corpus carcinoma had undergone a cyclic six-month course of therapy with only 5 mg NEA/day. Recurrent bleeding anomalies under therapy occurred less frequently among the patients treated with MPA than among those treated with NEA.