A 49-year-old normotensive man died after a series of strokes, slowly evolving dementia and personality change occurring over a period of 23 years. CT scan showed large infarcts involving the cortex and white matter of the temporo-occipital areas, small subcortical infarcts and low attenuation in the white matter of the frontal and parietal lobes. Neuropathological examination revealed large cortical and small subcortical infarcts corresponding to the radiological findings as well as degeneration/demyelination of central white matter corresponding to the areas of low attenuation seen on CT. The basic underlying pathological process was hyaline arteriosclerosis and atheroma which diffusely affected the small intracerebral arteries and to a lesser extent the arteries of the circle of Willis. Though usual because of the absence of hypertension, the very early age at onset of the syndrome and the presence of large cortical infarcts this case illustrates the clinical, radiological and neuropathological features of subcortical arteriosclerotic encephalopathy (Binswanger's type).