Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is a familial condition caused by a mutation of the Notch3 gen in chromosome 19. Accumulation of osmiophilic granular material (GOM) on the middle layer of small and medium-sized cerebral arteries leads to progressive narrowing of the blood vessels. As a result, clinical findings include migraine, cerebrovascular ischemic events, vascular dementia and a number of neuropsychiatric disorders associated to an extensive leukoencephalopathy readily shown by MRI studies. GOM deposits, however, are systemic and maybe shown ultrastructuraly on skin vessels by means of a biopsy. Detection of mutations of the Notch3 gen by molecular genetics may also allow accurate diagnosis during life. So far, there is no effective treatment for this disorder.