Postoperative radiotherapy for International Federation of Gynaecology and Obstetrics (FIGO) stage-1 endometrial carcinoma is a subject of controversy due to the low relapse rate and the lack of data from randomised trials. We did a multicentre prospective randomised trial to find whether postoperative pelvic radiotherapy improves locoregional control and survival for patients with stage-1 endometrial carcinoma.