We have examined 17 patients suffering from recurrent syncope caused by carcinoma of the head and neck. The tumor originated in the mouth in seven, larynx in six, nasopharynx in three and parotid gland in one, and involved cervical lymph nodes at diagnosis in 12. Sixteen patients had previously had radical neck dissections and 12 had had radiation therapy. Recurrent carcinoma was present in 16. Spells resolved spontaneously in four, improved with treatment in 11 and continued in two. The syncope was spontaneous in 15 and induced only by suctioning or carotid sinus massage in two. Suctioning also produced attacks in four others, as did carotid sinus massage in five of ten tested. Acute severe unilateral head or neck pain preceded spontaneous syncope in 11. Sixteen patients had both profound bradycardia and hypotension during most spells, but ten had syncope with hypotension only, either spontaneously or following cardiac pacing or atropine to prevent bradycardia. Seizure activity accompanied syncope in eight. Anticholinergics improved 7/12, carbamazepine 2/5, carotid ligation 1/1 and intracranial sectioning of the glossopharyngeal nerve 1/1. Local radiation may have helped 4/10. Cardiac pacing was ineffective in 3/3 due to the development of pure vasodepressive syncope. Autopsy in 2/2 showed tumor involving the glossopharyngeal and vagus nerves. Syncope in these patients is under-recognized, frequently is due to vasodepression, and suggests recurrent carcinoma.