Primitive neuroectodermal tumor or medulloblastoma (PNET/MB) is the most common malignant tumor of the brain in children. Recent progress in the management of this once almost uniformly fatal disease is illustrative of both the advances which have been made in the management of childhood brain tumors and the gaps in our understanding of childhood central nervous system malignancies. Using aggressive surgery and radiotherapy, more than 50% of children with this tumor can be expected to be alive and free of disease five years later. With detailed postoperative evaluation, children with PNET/MB can be stratified into two major subgroups: Those with an average prognosis and those with a poor prognosis. The addition of chemotherapy for children at the highest risk of relapse after treatment with radiotherapy results in an improved duration and rate of survival. However, treatment often results in significant endocrinological and intellectual sequelae.