Objective: In our investigation, we studied the patients with medulloblastoma who received 3-dimensional con- formal radiation therapy (3DCRT) and recorded their effects, side effects and failure reasons. Methods: From August 2001 to August 2007, 34 children with medulloblastoma were treated in our hospital. The age at diagnosis was 3-16 years old, and the mean age at diagnosis was 9.5 years old. Among all the patients, 16 cases were included in the high risk group and 18cases were included in the low risk group. All the patients were performed total resection or subtotal resection and no patientsreceived radiotherapy or chemotherapy before operation. All patients received 3DCRT within 3 weeks after resection. The dose of 30 Gy were given to the whole brain and whole spine, followed by 20-25 Gy boosted to the posterior brain fossa. The median fraction dose was 180 cGy. Every patient received the chemotherapy scheme of the Lomustine, Cisplatinum and Vincristine. Nobody received intrathecal chemotherapy. The tests of the complete blood count, blood biochemistry, hepatic and renal functions were required before every cycle of chemotherapy. Results: 5-year overall survival (OS) and 5-year disease free survival (DFS) were 71% and 62% respectively. The median follow-up time was 36.5 months. The 5-year OS of the high risk group was 71% compared to 62% of the low risk group. There were significant difference between the two groups (P = 0.01). There were 13 failure cases in all the patients. Of these 13 patients, 10 were dead and the other 3 were alive with tumor. The complete remission (CR) rate was 70.5% and the partial remission (PR) rate was 14%. Among the failure patients, there were 3 patients (8.8%) with the recurrences located in the brain of cribriform region. The 5-year OS of the patients with preoperative metastases was 12.5% (1/8), and which of the patients with residual tumor volume > 1.5 cm3 was 0% (0/5). Through the statistic analysis, it was found that both whether or not the metastases were found before surgery and residual tumor volume have the significant impacts on the prognosis of the children with medulloblastoma (P 1.5 c@ and preoperative metastases also had poor prognosis. It is needed to pay attention to the possible low dose of the brain of cribriform region.