Ependymomas in adults are rare and often misdiagnosed. This study reports on a series of adult patients with confirmed ependymoma treated at The University of Texas M. D. Anderson Cancer Center (MDACC). Patients aged >17 and with ependymoma were identified, and clinical data were collected by retrospective chart review. Descriptive statistics were used to describe the clinical data, Kaplan-Meier methods were used to generate survival curves, and Cox proportional hazards models were used to evaluate the association of clinical characteristics with survival. This series included 123 adult patients [51% male; median age 39 years (18-72)]. Forty had tumors in the brain, 80 in the spine, and 3 had both. The majority were Grade I/II lesions (108) vs Grade III (anaplastic; 15). Eighteen patients had tumors that were reclassified as ependymal tumors at MDACC. The most common presenting symptom was pain, with an average of 4 symptoms reported prior to diagnosis. Sixty-three percent of patients had a gross total resection, and 49% received radiation therapy. Average follow-up was 5.5 years, and 13% had died. Median time to recurrence was 21 months (Grade II) brain and 18 months (Grade III). Worse outcome measured by overall and progression-free survival were associated with brain location (P = .01, P = .04) and tumor anaplasia (P = .0025, P = .001). An MIB-1 > 10 was associated with worse outcome (P = .03). Tumor grade and brain location are associated with a worse prognosis. Reclassification of ependymoma by neuropathologists is common. Results of this study have lead to a multicenter study to further define important diagnostic and prognostic variables for adults with ependymoma.