Fibromuscular dysplasia of the internal carotid arteries is a rare condition that may cause transient ischemic attacks, stroke and death. The preferred method of treatment of symptomatic lesions is graduated dilatation. Over a six year period, we have dilated 18 lesions. During a follow-up period ranging from 13 to 70 months (mean: 48.3 months), none of the patients operated on has developed a stroke or 'hard' ocular/neurologic symptoms in the territory of the artery/arteries operated upon. Additionally, no patient has developed a stroke related to the contralateral asymptomatic, and consequently unoperated, carotid artery. Five patients with global symptoms have not had either carotid artery dilated and none has developed transient ischemic attacks or stroke during a follow-up period ranging from 22 to 100 months (mean: 42 months). These data demonstrate that a rational plan of management is dilatation of lesions associated with hard ocular/neurologic symptoms and nonoperative management of asymptomatic patients and patients with global symptoms.