This study tested the associations between metabolic syndrome, postprocedural myocardial injury, and clinical outcome after percutaneous coronary intervention. We evaluated 204 patients who fulfilled the study criteria and were scheduled for elective percutaneous coronary intervention. The patients were divided into a metabolic syndrome group and a control group according to the definition of metabolic syndrome. Creatine kinase-MB and troponin I levels were measured at baseline, at 8 h, and 24 h after the procedure, while clinical outcomes were followed up for 1 year. The incidence of postprocedural myocardial injury was significantly higher in the metabolic syndrome group than in the control group as indicated by either blood creatine kinase-MB elevation (32.9 % vs. 17.2 %, p = 0.010) or troponin I elevation (34.2 % vs. 17.2 %, p = 0.006). Postprocedural peak values of creatine kinase-MB (5.724 +/- 7.678 ng/ml vs. 3.097 +/- 5.317 ng/ml, p < 0.001) and troponin I (0.066 +/- 0.093 ng/ml vs. 0.038 +/- 0.079 ng/ml, p < 0.001) were also significantly higher in the metabolic syndrome group than in the control group. On multiple regression analysis, metabolic syndrome was independently associated with troponin I elevation (odds ratio 2.24, 95 % confidence interval, CI, 1.04-4.80, p = 0.039). During the 1-year follow-up, cardiac events occurred in 28.9 % of patients with metabolic syndrome and 17.9 % of controls, and there was a trend toward increased adverse outcomes in the metabolic syndrome group (hazard ratio 1.67, 95 % CI 0.93-3.00, p = 0.071, log rank test). The results of this study demonstrate that metabolic syndrome is associated with postprocedural myocardial injury and with increased cardiac events.