Vascular dementia and its most common subtype, multi-infarct dementia, are pathologically proven clinical entities. Their prevalence is not as high as previously thought, but they do represent a significant percentage of the population of demented patients. The diagnosis is more difficult to make than is the diagnosis of Alzheimer's disease; however, there are excellent criteria to guide the physician in making the diagnosis. At present the only treatment available is to control the risk factors responsible for the basic disease process; in the majority of cases this requires controlling hypertension.