Observation following gross-total resection (GTR) for non-anaplastic supratentorial ependymomas is often advocated based on small, retrospective series. The purpose of this study is to perform a population-based analysis to examine outcomes for this rare cohort of low-risk patients. A retrospective analysis was conducted utilizing the Surveillance, Epidemiology and End Results Program of the United States National Cancer Institute. We identified patients with supratentorial non-anaplastic ependymoma who underwent GTR alone or GTR followed by radiation. We identified 92 patients who met these criteria. The median age was 17.5 years (range 1-83) with the majority female (58 %) and white (75 %). Radiotherapy (RT) was delivered in half of patients. The 5-/10-year Kaplan-Meier estimated overall survival (OS) and cause-specific survival (CSS) for the overall cohort was 83.2/71.4 and 84.1/78.0 %, respectively. There was no evidence of decreased CSS (HR 0.52 [0.18-1.51]; p = 0.23) or OS (HR 0.63 [0.25-1.59]; p = 0.33) with the omission of RT on univariate analysis. Age ≥18 years correlated with worse OS (HR 4.01 [1.45-11.11]; p = 0.008) and CSS (HR 2.86 [0.99-8.31]; p = 0.05). RT did not impact outcome for this low-risk cohort of patients. Older age correlates with poor prognosis.