These consensus guidelines on adjuvant radiotherapy for early-stage endometrial cancer were developed from an expert panel convened by the American College of Radiology. The American College of Radiology Appropriateness Criteria® are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer-reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method; and Grading of Recommendations Assessment, Development, and Evaluation, or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment. After a review of the published literature, the panel voted on three variants to establish best practices for the utilization of imaging, radiotherapy, and chemotherapy after primary surgery for early-stage endometrial cancer.