Limited information exists about characteristics of patients with acute myocardial infarction (AMI) in Asia. We examined trends in interventional treatment and clinical outcomes for AMI from the Korea Acute Myocardial Infarction Registry (KAMIR). The study population was derived from patients in the KAMIR from November 2005 to December 2016. We identified 54,402 patients with ST-elevation myocardial infarction (STEMI) (n = 29,222) and non-ST-elevation myocardial infarction (NSTEMI) (n = 25,180). The rate of percutaneous coronary intervention (PCI) increased to 96.2% of STEMI group and 84.3% of NSTEMI group in 2016, respectively (All p_trend <0.001). Furthermore, the rate of successful PCI was 97.3% in STEMI and 97.9% in NSTEMI. The rate of primary PCI increased from 67.8% in 2005 to 96.9% in 2016 (p_trend <0.001). Moreover, in patients with STEMI, the proportion of drug-eluting stent implantation increased from 88.8% in 2005 to 97.9% in 2016 (p_trend <0.001). Regarding 1-year clinical outcomes, incidence of definite stent thrombosis was 0.5%, 0.6%, and 0.4% in patients with AMI, STEMI, and NSTEMI, respectively. Moreover, 1-year mortality of AMI improved almost 40% compared with in 2005 (11.4% in 2005 and 6.7% in 2015, p_trend <0.001). In Korean patients with AMI, the rate of primary PCI and drug-eluting stent implantation in STEMI was evidently higher than in the Western registries. In 1-year clinical outcomes, the incidence of stent thrombosis was low and mortality of AMI gradually improved and was lower than in the Western registries.