['Metabolic syndrome is common among patients having coronary artery bypass grafting. However, it remains unclear whether it has a significant impact on postoperative complications. We aimed to determine whether metabolic syndrome negatively influences the postoperative outcomes of coronary artery bypass grafting.', 'We enrolled 1183 patients who had coronary artery bypass grafting at Juntendo University Hospital between 1984 and 1992. Patients were categorized by the presence or absence of metabolic syndrome using the modified National Cholesterol Education Program Adult Treatment Panel III definition with body mass index in the place of waist circumference. Multivariate analysis was performed to assess the relationships between preoperative presence of metabolic syndrome and postoperative outcomes.', 'Metabolic syndrome was present in 551 (46.6%) patients and absent in 632 (53.4%). Postoperative stroke occurred in 4.7% of patients with metabolic syndrome and 2.1% of patients without metabolic syndrome (P < .0001). Postoperative acute renal failure occurred in 3.8% of patients with metabolic syndrome and 1.1% of patients without metabolic syndrome. On multivariate analysis, metabolic syndrome had odds ratios of 2.47 (95% confidence interval 1.22-4.99; P = .012) for postoperative stroke and 3.81 (95% confidence interval 1.42-10.3; P = .008) for postoperative acute renal failure.'] Is metabolic syndrome an independent risk factor for stroke and acute renal failure after coronary artery bypass grafting?