Concerns regarding long-term toxicities have led to the avoidance of post-operative radiation (PORT) in young children with intracranial ependymoma. We investigated the association between post-operative radiation therapy and overall survival (OS) in children younger than 3 years and compared their survival to other age groups. The study sample from the SEER database included 804 patients with intracranial ependymoma, grades 2-3, and diagnosed between 1988 and 2005. OS was estimated using the Kaplan-Meier method, and hazard ratios (HR) and 95% confidence limits (CL) were calculated based on multivariable Cox proportional hazards models. A total of 804 patients were selected and PORT was administered to 35% of patients younger than 3 years. With a median follow-up of 3 years (range 0.1-18 years), the 3 year OS was 61% for children younger than 3 years, 83% for those ages 3-20 years, and 69% for patients older than 20 years (P < 0.001). In multivariable analysis, OS was significantly improved for patients receiving PORT (HR 0.8, 95% CL 0.6-0.9), and gross total resection (HR 0.6, 95% CL 0.5-0.8). Among children younger than 3 years, the 3 year OS was significantly greater among those who received PORT compared to those who did not (81% vs. 56%, respectively, P = 0.005). The majority of children younger than 3 years with intracranial ependymoma did not receive PORT. Children younger than 3 years who did not receive PORT had a relatively poor outcome, while those who received radiation therapy had a survival similar to older patients.