One hundred forty-four patients with clinical stage I endometrial adenocarcinoma were treated over an 11-year period at Madigan Army Medical Center and Brooke Army Medical Center. Following surgical staging, 44 selected patients were placed on oral estrogen replacement for a median duration of 64 months. In the estrogen user group, there were no recurrent endometrial cancer and no intercurrent death. Of the 99 nonestrogen users, there were 8 recurrences (8%) and 8 intercurrent deaths. Patients placed on estrogen replacement had low-risk factors for recurrence, namely, low tumor grade (grades 1 and 2), less than 1/2 myometrial invasion, and no metastases to lymph nodes or other organs. Postoperative estrogen replacement appears to be safe in selected low-risk patients.