A 17-year-old boy with neurofibromatosis presented with delayed puberty and epileptic seizures of recent onset. A computed tomographic scan revealed aqueductal stenosis due to a tumor of the aqueduct. This tumor was found at autopsy to be a pilocytic astrocytoma. Aqueductal stenosis in neurofibromatosis is uncommon and has been considered to be a result of periaqueductal gliosis. This seems to be the first report of neurofibromatosis associated with a tumor of the aqueduct.