PURPOSE: The outcome and prognostic factors of brainstem glioma were evaluated following radiotherapy methods. MATERIALS AND METHODS: Between 1986 and 2001, 45 childhood patients with diffuse brainstem glioma were treated. There were 26 boys and 19 girls, with a median age of 7 years (range 3~18). The histopathological diagnoses were confirmed in 13 patients, which revealed a low-grade glioma in four patients, and high-grade glioma in the other nine. Before 1993, radiation therapy using a regime of 1.8 to 2.0 Gy once a day was performed in 16 cases; thereafter, a regimes of 1.1 or 1.5 Gy twice a day was given in 15 and 14 cases, respectively. Nine patients were treated with adjuvant chemotherapy. The response to the treatment was evaluated by the MRI findings 4 weeks after radiotherapy. RESULTS: After radiotherapy, the neurological deficit improved in 42 of the 45 patients (93%). The MRI responses were as follows; partial response 22/39 (56%), minimal to no response in 16/39 (41%) and tumor progression in 1/39 (3%). The median time to disease progression was 7 months, and the median survival was 12 months; the overall survival rate at 1 year was 41%. There was no significant prognostic factor for overall survival. The progression-free survival was influenced by the tumor histology (low grade vs. high grade, p=0.05) in those patients whose pathology was confirmed. CONCLUSION: The radiation therapy fractionation schedule did not influence the survival. Low grade histology was a possible favorable prognostic factor of progression-free survival in pediatric brainstem glioma patients.