Treatment and outcome in 31 cases of recurrent medulloblastoma arising in childhood are described. As initial treatment, all patients underwent some degree of tumor resection, and 28 patients received radiation therapy postoperatively. The younger children tended to have recurrence earlier after the initial treatment and to die sooner after recurrence than the older children. Early recurrences (within the first 2 postoperative years) often took the form of spinal subarachnoid dissemination, whereas late recurrences (after more than 2 years postoperatively) most often involved intracranial regrowth. Patients who underwent extensive tumor resection and received higher doses of radiation to the entire neuraxis generally had longer remission than those who had less extensive tumor removal and lower doses of radiation. Two of four patients who received intrathecal chemotherapy with methotrexate, cytosine arabinoside, and hydrocortisone as part of the initial treatment had remission lasting more than 3 years. The usual treatment for recurrent medulloblastoma was reirradiation, which generally improved survival time. Tumor removal plus intrathecal chemotherapy in selected cases of recurrence also provided abatement of symptoms. Early recurrence was usually difficult to control, whereas treatment for late recurrence was generally palliative but not curative. Average survival was 4.3 months after early recurrence, and 21.9 months following late recurrence. Two of the nine patients subjected to autopsy had no local recurrence but had extensive spinal subarachnoid dissemination. At the time of initial extensive tumor resection, irradiation or intrathecal chemotherapy, or both, should be added to prevent regrowth of the tumor and subarachnoid dissemination.