Oligodendrogliomas are uncommon intracranial tumors of childhood, especially when these tumors arise in the posterior fossa. Oligodendrogliomas are usually treated with local radiation therapy. The authors report four children, median age 7.5 years, cared for over a 7-year period, who had oligodendrogliomas (all histologically malignant) of the cerebellar region. Three patients received local radiation therapy and all had recurrent disease at a median of 11 months posttreatment outside their radiation field; at the time of relapse, disease at the primary tumor site was stable. One child treated with craniospinal and local radiation therapy is disease-free 15 months after diagnosis. These results suggest that oligodendrogliomas of the posterior fossa should be considered potentially malignant lesions and treated with local plus presymptomatic craniospinal radiation therapy.