A case of Alexander's disease in a 39-year-old man is reported. The clinical course was characterized by headaches and cerebellar gait for 6 months. A state of acute unconsciousness followed, lasting 2 days. Subsequently, dysfunction of the lower cranial nerves on the left-side, left-sided motor incoordination, and a right-sided spastic hemiplegia were found. The patient died 49 days after an acute incident of lung embolism. Neuropathologically generalized and focally pronounced Rosenthal fibers in subpial, subependymal, and perivascular regions were found. They were especially predominant in the brain stem and cerebellum. Atypical fibrillary glia, moderate patchy demyelination, and circumscribed cystic necrosis in the brain stem were also observed.