Seventeen adult patients with medulloblastoma were treated at Rush-Presbyterian-St. Luke's Medical Center and affiliated hospitals between 1969 and 1986. All patients had a surgical procedure (total excision in seven patients, partial resection in nine patients, and biopsy alone in one patient) followed by radiation therapy to the craniospinal axis. The 5-year actuarial survival rate is 77% with a disease-free survival of 58%. Five patients have relapsed in the posterior fossa, one in the brain parenchyma, and two in osseous sites. Two of the local relapses occurred more than 4 years after initial treatment. Patients undergoing “total” resection of the tumor fared better than those with partial resection or biopsy only. Local failure was uncommon with posterior fossa doses > 55 Gy, and there was a trend toward better local control when the radiation therapy was completed in less than 7 weeks. The histologic indicators of poor outcome were necrosis, high mitotic index, and “classical” histologic appearance.