Vimentin immunoreactivity was examined in brain tissues from non-neurological and various human central nervous system disease cases. In all brain tissues examined, vimentin immunoreactivity was intensely positive in ependymal cells and subpial tissues, and weakly positive in some capillaries and some white matter astrocytes. In affected areas of Alzheimer's disease (AD), Pick's disease, amyotrophic lateral sclerosis (ALS), multiple sclerosis (MS) and cerebral infarction cases, numerous intensely vimentin-immunopositive astrocytes of both protoplasmic and fibrous morphology were demonstrated. A few such astrocytes were also observed in Parkinson's disease and progressive supranuclear palsy. ALS, MS and infarction brains also had numerous, strongly vimentin-positive, round and fat-laden microglia/macrophages. In AD and ALS, a few reactive microglia with irregularly enlarged shapes were vimentin positive. In AD, they were almost exclusively related to senile plaques.