A 42-year-old man with generalized atherosclerosis underwent surgery of the left carotid artery with eventual placement of a Dacron graft bypassing the left carotid sinus. Subsequently, symptoms suggestive of pheochromocytoma developed, and 24-hour urine catecholamine levels were elevated. Clonidine testing resulted in suppression of plasma norepinephrine levels but was complicated by severe hypotension and a transient ischemic attack. Baroreceptor dysfunction may have been involved. Caution is advised and recommendations are offered for future usage of the clonidine suppression test.