Hypersensitive carotid sinus is a rare cause of spontaneous syncopal attacks. It must be differentiated from the other more common causes, such as intrinsic cardiac disease, vasovagal responses, postural hypotension and cerebrovascular insufficiency, although it may accompany these conditions. The definition of carotid sinus syncope is syncope elicited by stimulation of a hypersensitive carotid sinus. Nineteen patients with carotid sinus syncope were treated by carotid sinus denervation. Ages ranged from 48 to 83 with a mean of 65.5 years. Symptoms of marked dizziness or syncope were reproduced by gentle compression over the carotid bifurcation, while ECG monitoring revealed bradycardia or transient asystole. Seventeen patients had carotid arteriograms, eleven of which were normal. One patient had stenosis of the external carotid artery, while five had stenosis of the internal carotid. The right carotid sinus was involved in ten patients, the left in three and both sides in six. All patients underwent unilateral or bilateral carotid sinus denervation. Five patients with internal carotid stenosis had concomitant carotid endarterectomy. Complete relief of symptoms or marked improvement was noted in all but one patient. Postoperative follow-up ranged up to 15 years. Carotid sinus denervation is a simple, effective method of treating this disorder.