Objective. To determine the outcomes of patients with intermediate-risk Stages IC and II uterine corpus cancer treated with surgery alone or surgery followed by radiation therapy. Methods. Patients with uterine corpus cancer diagnosed in 1995 were identified from hospitals in the United States with tumor registry databases. Data were collected on histology, surgical treatment, radiation therapy, recurrence, and survival. Survival analysis was performed using life-table computational method. Results. 713 hospitals submitted data on 10,726 patients with uterine corpus cancer. 9977 patients (93.0%) underwent surgery, and 2624 patients (26.3%) received radiation therapy. Patients with clinical Stages IC and IIA disease who underwent surgery followed by radiation therapy compared to surgery alone had a trend toward improved 5-year relative survival (RS) (81.2% vs. 92.5%; 74.3% vs. 96.0%, respectively). The 5-year RS of patients with surgical Stage IC disease was not statistically different between the surgery alone group and the radiation group (93.9% vs. 91.7%). Patients with surgical Stage IIA and IIB disease did not benefit from radiation therapy compared to surgery alone (5-year RS; 83.7% vs. 98.0% and 82.3% vs. 81.8%, respectively). Conclusion. There is a trend toward improved survival in patients with clinical Stages IC and IIA uterine corpus cancer when radiation therapy is utilized following surgery. The survival of patients with surgical Stages IC and II uterine corpus cancer is not improved with adjuvant radiation therapy. © 2005 Elsevier Inc. All rights reserved.