Extremely high concentrations of human chorionic gonadotropin in the cerebrospinal fluid were found in a 5-year-old boy presenting sexual precocity and leg pain. An intramedullary spinal cord tumor was revealed by myelogram and metrizamide computerized tomography, and a biopsy specimen taken at laminectomy. Histologically, the tumor showed germinoma with syncytiotrophoblastic giant cells. The tumor remitted for 5 months after irradiation of 3500 rad and chemotherapy, but recurred in spite of adding 7500 rad and more aggressive chemotherapy. No relapse has been seen for 1 year after amputation of the spinal cord at the T7 level.