Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is a genetically linked neurologic disease characterized by recurrent strokes and progressive or stepwise dementia, with or without migraine-like headaches, seizures, and pseudobulbar palsy. We describe a patient referred with a diagnosis of treatment-refractory primary angiitis of the central nervous system. Meningocortical and skin biopsies confirmed that the patient had CADASIL. Clinical and radiographic differences in these disorders may be subtle, but awareness of them is crucial if the patient is to avoid unnecessary exposure to potentially deleterious immunosuppressive therapy.