Endometrial cancer is the most common gynecologic malignancy in the U.S., with an increasing incidence likely secondary to the obesity epidemic. Surgery is usually the primary treatment for early stage endometrial cancer, followed by adjuvant therapy in selected cases. This includes radiation therapy [RT] with or without chemotherapy, based on stratification of patients into categories dependent on their future recurrence risk. Several prospective trials (PORTEC-1, GOG#99, and PORTEC-2) have shown that the use of adjuvant RT in the intermediate risk (IR) and the high-intermediate risk (HIR) groups decreases locoregional recurrence (LRR) but has no effect on overall survival. The ad hoc analyses from these studies have shown that an even larger LRR risk reduction was seen within the HIR group compared with the IR group. Vaginal brachytherapy is as good as external beam radiotherapy in controlling vaginal relapse where the majority of recurrence occur, and with less toxicity. In the high-risk group, multimodality therapy (chemotherapy and RT) may play a significant role. Although adjuvant RT has been evaluated in many cost-effectiveness studies, highquality data in this area are still lacking.The uptake of the above prospective trial results in the U.S. has not been promising. Implications for Practice: Several phase III randomized controlled trials have shown that adjuvant radiation for highintermediate risk early-stage endometrial cancer confers a benefit by reducing local regional recurrence with minimal added toxicity, but at increased cost and without significant overall survival benefit. This article reviews key trials regarding adjuvant radiation in early stage endometrial cancer and summarizes current clinical practice patterns and available guidelines. These facets must be considered and reviewed with each patient individually to determine the relative benefit to each patient.