Background: There are very limited data regarding role of trimetazidine in managing acute myocardial infarction. This analysis from the Korean Acute Myocardial Registry (KAMIR) assessed the beneficial effects of in-hospital trimetazidine therapy for the improvement of long term clinical outcomes in acute myocardial infarction (AMI) patients. Methods: A total 14871 AMI patients (63.4 짹 12.7 years, 9877 males) enrolled in the KAMIR study from November 2005 to April 2008 were divided into two groups; trimetazidine therapy group or control. We retrospectively evaluated the effects of trimetazidine therapy on in-hospital death and major adverse cardiac events including cardiac death, recurrent myocardial infarction, revascularization during one-year clinical follow-up. Results: 8840 patients were censored at various times in the registry. The trimetazidine therapy group was 242 (2.4 %) and control group was 9667 (97.6 %). The baseline clinical characteristics were similar between the two groups. The rate of in-hospital death was significantly lower in trimetazidine therapy group (1.5 % vs. 5.2%, p=0.003). The incidence rate of MACE during one-year clinical follow-up was significantly lower in trimetazidine therapy group (3.3 % vs. 13.7 %, p<0.001). Multivariate Cox regression analysis revealed that trimetazidine therapy was a significant predictor of favorable prognosis. (P=0.004, hazard ratio: 0.228; 95% confidence interval: 0.084-0.615) Conclusion: Trimetazidine therapy was beneficial for long-term outcome of AMI patients.