A boy with juvenile onset of symptoms of Alexander's disease had a clinical picture of pseudobulbar palsy, ataxia, and spastic paraparesis. Pathologic examination of the central nervous system revealed the diffuse presence of Rosenthal fibers and patchy demyelination. This may be the first report of a case with significant neuronal changes and inflammation within the brain stem in this disease. The clinical picture of this entity is varied and age-dependent. Alexander's disease may be a motor system specific entity secondary to astrocytic dysfunction.