Between 1981 and 1991, 11 adults over 16 years of age were treated for medulloblastoma at the authors' institutions. These patients were studied retrospectively. The patients were managed uniformly, and the treatment included extensive surgical resections and radiation therapy. Chemotherapy was used on only three patients with recurrence. Probable prognostic factors, including tumor location, extent of surgical resection, dose and extent of radiation therapy, and histological characteristics of the tumor such as neuronal or glial differentiation and desmoplasia were investigated. The classical form of medulloblastoma was present in seven cases while the desmoblastic subtype was found in four cases. All patients with the desmoplastic form had the tumor in cerebellar hemisphere. Gross total removal of the tumor was achieved in seven patients and subtotal excision in four patients. There was no surgical mortality in our series. The extent of surgical resection and location of the tumor had an important effect on longterm survival. The extent and dose of radiation therapy had a major effect on recurrence-free survival. Survival rates were best for patients receiving high-dose irradiation to the entire neuroaxis. Other factors such as age and sex had no major effect on prognosis.