Background : Myocardial injury during percutaneous coronary intervention(PCI) occurs in 10~40% of cases. Several studies showed that adenosine and nicorandil have myocardial protective effects against angioplasty-related myocardial injury. We conducted a prospective, randomized, open-label study to investigate the effect on myocardial protection of intracoronary adenosine and nicorandil combination therapy. Methods : 193 patients were enrolled who were scheduled to undergo non-urgent PCI for denovo native coronary lesions with stable or unstable angina between November 2007 and June 2008. All patients were pretreated with aspirin and clopidogrel. Patients were randomized to group I (control saline, n=50), group II (adenosine 50ug, n=48), group III (nicorandil 4mg, n=48), and group IV (adenosine-nicorandil combination, n=47). Myocardial necrosis was assessed by elevations of creatine kinase MB isoform (CK-MB), tropinin I (TnI) before PCI and 6h, 12h, 24h after PCI. Primary endpoint is incidence of myocardial necrosis (elevation of serum TnI) and secondary endpoint is mean CK-MB value and post-procedural myocardial infarction (MI). Results : No significant differences were observed among the four groups in terms of the baseline characteristics and laboratory findings. There were no significant diffenence in the incidence of postprocedural myocardial necrosis between each groups (15.7, 15.6, 20.4, 11.1%, respectively, p=0.716). There were no significant diffenence in the incidence of postprocedural MI between each groups (3.9, 4.4, 0, 8.3%, respectively, p=0.268). At 6h after PCI, there were no significant differences in the change of cardiac enzyme among four groups; ��CK-MB (-0.1짹1.8, 0.7짹4.3, -0.2짹1.5, -0.5짹3.4, p=0.364), ��TnI (0.10짹0.39, 0.02짹0.14, 0.13짹0.62, 0.16짹0.67, p=0.627). At 12h after PCI, there were no significant differences in the change of cardiac enzyme among four groups; ��CK-MB (p=0.779), ��TnI (p=0.579). No serious adverse event were observed during study except transient AV block and hypotention. Conclusions : Pretreatment with intracoronary adenosin, nicorandil and combination of two drugs could not reduce the incidence of myocardial necrosis and MI after non-urgent PCI.