Cerebral autosomal dominant arteriopathy with subcortical infarcts and leucoencephalopathy (CADASIL) is caused by mutations in the gene which maps to the short arm of chromosome 19 and encodes the NOTCH3 receptor protein, predominantly expressed in adults by vascular smooth muscle cells and pericytes. The receptor has a large extracellular domain with 34 epidermal growth factor-like repeats encoded by exons 2-24, the site at which CADASIL mutations are most commonly found. Migraine with aura is often the earliest feature of the disease, with an increased susceptibility to cortical spreading depression suggested as a possible aetiological mechanism. Stroke, acute encephalopathy and cognitive impairment can also occur. Hypertension and smoking are associated with early age of onset of stroke. It diffusely affects white matter, with distinct findings on T2- weighted MRI, involving the external capsule, anterior poles of the temporal lobe and superior frontal gyri, displaying a characteristic pattern of leucoencephalopathy. Affected individuals have a reduced life expectancy. An effective treatment for CADASIL is not available. The authors describe a 35-year-old manwith an unremarkable medical history, presenting to the emergency department with slurred speech and increased confusion 3 days following a fall. He was a smoker and consumed 16 units of alcohol weekly. He was hypertensive and tachycardic. Physical examination confirmed increased tone in his lower limbs and dysarthria. His CT head showed severe cerebral atrophy, multiple small old infarcts and moderate background microvascular disease. Further investigation with an MRI head confirmed multiple white matter abnormalities with microhaemorrhages. The possibility of a hereditary vasculopathy was rendered as the appearances were thought consistent with a diagnosis of CADASIL. Genetic testing identified the gene thus confirming the diagnosis. This paper provides an overview of the aetiology, clinical presentation, pathogenesis, investigations and management of CADASIL.