Binswanger's encephalopathy is reviewed in respect to history, computed tomography, magnetic resonance imaging, epidemiology, pathology, clinical picture, laboratory findings, differential diagnosis, and treatment. The various viewpoints on the pathogenesis of the process are discussed, in particular the role of ischemia, vascular disease, high blood pressure, lacunar infarction, hypoxia, edema, and hydrocephalus. The white matter hypomyelination of congophilic angiopathy and Alzheimer's disease should provide clues. A unifying hypothesis has not been attained.