Nine patients, 8 with medulloblastoma and 1 with ependymoblastoma, were treated with intrathecal colloidal Au198. Six of these patients were treated for cure using a combination of surgery, total neuraxis irradiation from external sources, and the intrathecal radionuclide. Five of these patients are alive and free of disease for periods ranging from 12 to 42 months (32 months median). The cauda equina syndrome, a complication encountered in some patients treated earlier with intrathecal radiogold, appears to have been avoided with the use of a new technique. This calls for the use of smaller doses of radionuclide, and prompt cephalad flow of the radioactive material by tilting the head down immediately after instillation of the isotope. A projected long-term survival (3 years or more) of 75 per cent in a collected group of patients is encouraging.