We describe 2 normotensive sisters presenting slowly progressive dementia associated with acute or subacute focal neurological symptoms, unilateral or bilateral motor signs, and dysarthria. Their father, who died in the seventh decade, had a similar clinical picture. Computerized axial tomography (CT) scan of the head showed symmetrical hypodensities in the periventricular white matter and mild to moderate hydrocephalus. In these patients a diagnosis of Binswanger's disease was based on the clinical features supported by white matter changes on CT scan. Our study suggests that genetic factors may play a role in the etiology of Binswanger's disease.