Backgrounds: The optimal loading dose of clopidogrel in patients (pts) with acute myocardial infarction (AMI), specifically in Asian population is not fully investigated yet. We compared bleeding and vascular complications, mid-term outcomes of a 300- versus 600-mg loading doses of clopidogrel in AMI pts. Methods: A total 355 consecutive AMI pts (Age; 60.62 짹 11.87, Men; 70.7 %) who underwent percutaneous coronary intervention (PCI) with drug-eluting stents (DESs). The standard dose group (n=251 pts) was given 300-mg loading doses of clopidogrel and the high dose group (n=104 pts) was given 600-mg before PCI. The bleeding and vascular complications, in-hospital, angiographic and clinical outcomes up to 6-month were compared between the two groups. Results: Baseline clinical and procedural characteristics were similar between the two groups. In-hospital bleeding and vascular complications were similar between the two groups. Nadir Hb and platelet were similar between the two groups. The frequency of transfusion was similar between the two groups. At 6-month, angiographic outcomes were similar between the two groups. Moreover, there were no differences in 6-month clinical outcomes including mortality, myocardial infarction, repeat PCI and major cardiac adverse event (MACE) between the two groups (Table). Conclusion: Pretreatment with a 600-mg loading dose of clopidogrel in a series of Asian population is similarly safe and effective as compared with the 300-mg in pts with AMI undergoing PCI with DES.