Abstract: Objective：To evaluate the protective effect of trimetazidine on myocardial injury by percutaneous coronary intervention(PCI).Methods：Seventy-two cases with stable or unstable angina were randomly divided into control group(n=34) and trimetazidine group(n=38).Treatment group received trimetazidine of 20 mg three times a day for 7 days before PCI) and Continuous oral three months after PCI.Control group did not receive trimetazidine.All cases(n=72) were administered aspirin and conventional drugtreatment.The cardiac troponin Ic(cTnI) and creatine kinase-MB(CK-MB) levels of each case were measured at 6,24 hour and left ventricular ejection fraction were also detcted at 1,3 month before and after PCI.Results：In all cases,the cardiac troponin Ic(cTnI) and creatine kinase-MB(CK-MB) levels had no significantly difference(P〉0.05)before PCI,but its levels of trimetazidine group were also significantly lower than that of control group throughout procedure after PCI.Left ventricular ejection levels of trimetazidine group were also significantly higher than control group at 1,3 month after PCI(P〈0.01).Conclusions：Using trimetazidine before PCI can significantly reduce myocardial injury PCI-induced,and improves left ventricular contractility function.