The role of cytology of cerebrospinal fluid (CSF) has not been established in pediatric ependymoma. Thirty-two children with metastatic ependymoma were analyzed: 11 patients had only positive CSF cytology, 6 had only positive magnetic resonance imaging (MRI) findings, and 15 had both CSF cytology and MRI positive. Twenty-two patients relapsed. Five-year event-free survival was 27.3%+/-13.4% for children with only CSF positive (M1) versus 26.1%+/-10.2% for patients with positive spine MRI positive (with or without CSF positive, M3) (P=0.87). In conclusion, 34% of the patients with metastatic ependymoma were identified based on CSF cytology only and their outcome was comparable to patients with macroscopic disease. CSF cytology is a useful tool to stage newly diagnosed patients with ependymoma.