A multicentre trial on patients with apparent stage I endometrial carcinoma was conducted with the aims of defining a treatment plan on the basis of the pathological disease extension and of evaluating the effectiveness of adjuvant medroxyprogesterone acetate (MPA). After surgery, patients with disease limited to the endometrium did not receive any further treatment. Patients with inner myometrial invasion and well or moderate differentiation were randomised to no further treatment vs. MPA 100 mg orally twice a day for 12 months; patients with moderate or deep myometrial invasion or undifferentiated grade were randomised to radiotherapy on pelvis vs. radiotherapy plus MPA, and patients with node-positive disease (N+) were submitted to radiotherapy on pelvis and para-aortic nodes vs. radiotherapy plus MPA. At 84 months, analysis as intention to treat on 856 patients shows a high relapse-free survival, whereas it did not show any significant difference between the MPA-treated and untreated groups. The study indicates that relapse-free survival is influenced by a treatment based on the pathological extension of the disease and that adjuvant hormonotherapy does not improve the cure rate.