A prospective study was devised in 1980 to assess the effect on survival of neoadjuvant Provera as part of the primary treatment of endometrial carcinoma in conjunction with surgery and radiotherapy. Between June 1980 and June 1985, 218 patients with Stage I adenocarcinoma of the corpus uteri were allocated on the basis of hospital of presentation to receive either neoadjuvant treatment with medroxyprogesterone acetate (MPA) 100 mg t.i.d. p.o. from diagnosis for 90 days, or no adjuvant treatment (the control group). The minimum follow-up was 5 years. There was no significant difference between the overall actuarial survival in the treatment group (123 cases) and that in the control group (95 cases). This was 83.7% and 69.2% at 5 and 10 years respectively in the treatment group and 78.9% and 70.7% in the control group (P > 0.1).