Non-atherosclerotic cerebrovascular disorders are considered to occur less frequently than those caused by embolic or thrombotic disease. Such sporadic disorders resulting from direct effects on the cerebral or peripheral vasculature include hypertensive small vessel disease, vascular inflammatory conditions, aneurysms and arteriovenous malformations. Remarkably, some of these are also inherited in an autosomal dominant manner and appear to entail degeneration or abnormal differentiation of blood vessel wall elements such as smooth muscle, endothelial cells, pericytes and the perivascular nerve plexus. Two intensively investigated examples of these include the cerebral amyloid angiopathies and distinct primary arteriopathies such as CADASIL. The identification of novel genes associated with the hereditary forms of cerebrovascular disorders has been invaluable to understanding of the pathogenesis and management of sporadic disease.