Background Intra-coronary nicorandil infusion has been reported to increases coronary artery blood flow and improves other physiological parameters. Periprocedural myocardial infarction (PMI) is a frequent and prognostically important complication of percutaneous coronary intervention (PCI). However, there is limited information on the prevention of PMI. A prospective randomized single center study was designed to evaluate the efficacy of intra-coronary nicorandil on PMI after elective PCI.Methods 90 patients with stable and unstable angina were randomly assigned to the nicorandil group (n=41) or a control group (n=49); all patients had a PCI at LAD. In the nicorandil group, 4 mg of intra-coronary nicorandil was infused prior to PCI (2 mg before ballooning, 2 mg before stenting). We measured Post-PCI peak levels of markers of myocardial injury (CK-MB and Troponin-I) and we also reviewed angiographic findings of patients to analyze stent jail and to obtain jail index. Jail index is defined as the numbers of side branches occluded or reduced TIMI flow divided by total numbers of side branches.Results The baseline characteristics were similar in both groups. The mean post-PCI peak CK-MB level were 2.81짹2.43 關g/L in nicorandil group, 1.85짹1.79 關g/L in control group and mean post-PCI peak troponin I level were 0.53짹0.68 ng/mL in nicorandil group, 0.35짹0.54 ng/mL in control group. There was no statistical significance (p=0.065 for CK-MB, p=0.154 for TnI). The jail index was 0.077짹0.21(n=37) in nicorandil group(n=41) and 0.074짹0.19(n=45) in control group(n=49). Also there was no statistical significance in jail index (p=0.823).Conclusion Intra-coronary nicorandil infusion showed no efficacy on periprocedural myocardial infarction in elective percutaneous coronary intervention of stable and unstable angina.