OBJECTIVES--To review the results of surgical revascularisation for left main coronary artery stenosis and the associated vascular pathology that is responsible for cerebrovascular complication. PATIENTS--60 patients (45 men, 15 women) (mean age 61.3 (39-79)) who underwent revascularisation for stenosis of the left main stem coronary artery (LMS) between January 1987 and August 1990 were compared with an age and sex matched control group of patients undergoing revascularisation for triple vessel disease during the same period. OUTCOME MEASURES--In-hospital morbidity and operative mortality. RESULTS--24 patients in the LMS group presented with unstable angina. The left ventricular ejection fraction was less than 50% in 30 patients and less than 30% in nine. 17 patients (28%) had large vessel extracranial carotid artery disease and 10 patients had vascular disease of the lower limbs. In six patients atheromatous plaques were noted in the ascending aorta during surgery. There was no in-hospital mortality. In-hospital morbidity included neurological deficits in five (8.3%), arrhythmias in seven (11.6%), and pulmonary complications in six (10%) patients. The incidence of carotid artery disease in the LMS group was significantly higher (p = 0.04). Atheromatous plaque in the ascending aorta and postoperative neurological complications were more common patients with LMS. CONCLUSIONS--The incidence of carotid artery disease was higher and postoperative cerebrovascular complications were more common in patients who had coronary artery revascularisation for stenosis of the left main stem coronary artery. The early surgical results were excellent. These findings suggest that for optimum perioperative management patients with stenosis of the left main coronary artery should be screened for carotid artery disease before bypass surgery.