High-risk endometrial cancer comprises an uncommon group of tumors, which includes pathological stage III adenocarcinoma and all stages of papillary serous carcinoma. Optimal management of this class of malignant female genital neoplasms is surgical resection, including debulking of any gross abdominopelvic disease. This article analyzes the literature concerning the use of adjunctive radiotherapy. The data presented suggest that postoperative whole abdominal radiotherapy may improve outcome in selected subsets of patients within this high-risk group. Future clinical investigations will greatly benefit from the anticipated published results of two completed prospective cooperative group clinical trials that involve whole abdominal irradiation.