Widespread utilization of angiography has allowed discovery of fibromuscular hyperplasia affecting medium-sized arteries throughout the body. Such arterial dysplasia of the carotid and vertebral arteries is rare. However, as experience accumulates, it is becoming increasingly evident that this may be an important entity in these locations. Its significance derives from the fact that it may produce cerebral ischemia or infarction in persons of any age. The fact that this condition is frequently associated with intracerebral aneurysms and with fibromuscular hyperplasia of the renal artery suggests that it is a generalized arterial abnormality of common etiology. This communication details the clinical aspects of five patients with fibromuscular hyperplasia of the carotid and vertebral arteries. In one instance, this condition affected the vertebral arteries, in three, the carotids alone, and one, both the carotids and the vertebrals. The object of this presentation is to emphasize the diverse symptomatology, the association with other