Osteoblastic bony metastases were observed in a case of medulloblastoma three years after surgery and radiation treatment. There was clinical response to COP therapy (cytoxin, oncovin, prednisone). Radiographic and isotopic bone scan study showed uniform increase in bone density. Serum calcium and phosphorous and acid phosphatase levels were normal. Alkaline phosphatase was elevated and declined with therapy without change in the bone appearance. This suggested an increase in bone deposition activity. However, no increase in calcitonin level was detected either during active disease or following a chemotherapy-induced remission.