Cerebral autosomal dominant arteriopathy with subcortical infarcts and leucoencephalopathy (CADASIL) is an inherited arterial disease, commonly overlooked or misdiagnosed. We report a case of CADASIL in a 51 years old woman who presented with progressive subcortical dementia, recurrent ischemic events and seizures in the absence of known vascular risk factors of five years' duration. Her mother had a history of similar illness. Magnetic resonance imaging (MRI) of brain revealed subcortical and deep white matter hyperintense lesions within the cerebral white matter on T2-weighted images. DNA mutation of Notch 3 gene confirmed the diagnosis of CADASIL.