BACKGROUND.Gliomatosis cerebri (GC) is a rare and typically fatal glial neoplasm of the central nervous system. In this report, the authors describe the largest cohort of children to date with GC and explore relations between potential prognostic factors, treatment, and survival.METHODS.Imaging, pathologic, and outcome data were reviewed from 13 patients who were diagnosed with GC and were treated at the Children's Hospital of Philadelphia (CHOP) between 1982 and 2005. All patients had GC confirmed by biopsy. Twelve patients received cranial irradiation, and 8 of those patients received adjuvant chemotherapy. A single patient age 1 year received chemotherapy alone. A review of the literature identified 51 pediatric patients with GC.RESULTS.The progression‐free survival rate in this study was 13% (range, 1.5–43 months), and the overall survival (OS) rate was 64% (range, 6.5–67 months) at 2 years. OS was significantly shorter for patients who presented in the first decade of life (P = .04). The time to progression was prolonged significantly for patients who had no evidence of tumor enhancement on imaging studies (P = .03). When survival data from patients reported in the literature were combined with the CHOP cohort, treatment prolonged OS significantly (P = .003).CONCLUSIONS.The outcome of pediatric patients with GC was extremely poor; however, the current results indicated that treatment may prolong OS. Age < 10 years and contrast enhancement on magnetic resonance imaging studies at diagnosis may be risk factors for shorter survival in pediatric patients with GC. Cancer 2006. © 2006 American Cancer Society.