This is the sixth report of a disease first described by Alexander in 1949.1 Several names have been given to this cerebral disorder (Table), but the eponym "Alexander's disease" will be used herein. The main neuropathological characteristic was granular, eosinophilic deposits at all interfaces of the central nervous system; that is, in the perivascular tissue and at the pial surface. Five of the cases were also characterized by megalencephaly, leukodystrophy, and an onset of the disease shortly after birth followed by death in a few years (Table). Clinical History The present case pertains to a boy who died at age 22 months. No instances of epilepsy or nervous disorders were known in the family. The prenatal history and birth were normal, except for a slight toxemia during pregnancy. The disease started at 41/2 months, allegedly subsequent to immunization with poliomyelitis vaccine, when the child experienced high fever and convulsions.