The terms Binswanger's disease and arteriosclerotic subcortical encephalopathy are often applied to elderly patients with dementia and a diffuse hypodensity of the white matter on CT scan (or increased signal on MRI). Recently, similar white matter abnormalities have been reported in non-hypertensive patients with Alzheimer's disease and in elderly healthy people, casting doubt upon Binswanger's disease as an entity. These findings also suggest that the descriptive term leukoaraiosis meaning rarefied white matter is more appropriate than the term leucoencephalopathy. Nevertheless, within the group of patients with an ischemic stroke, several data suggest that leukoaraiosis is not a fortuitous finding and does not simply reflect ageing. Actually, these patients have a particular clinical profile, with intellectual deterioration, chronic hypertension, usually patent carotid arteries, and a deep location of the presenting infarct. Moreover hypertension seems to be still more strongly associated with leukoaraiosis than with a deep location of the infarct (lacunar infarction).