Background: Recent trials showed that drug-eluting stent (DES) implantation was superior or equivalent to bare-metal stent (BMS) implantation in primary stenting for acute ST elevation acute myocardial infarction (STEMI) in term of target vessel failure. But there was little data regarding long-term (3-year) efficacy and safety of DES and BMS in primary stenting. Methods: We evaluated 596 patients treated with at least 1 DES (n=270) or BMS (n=326) from January 2003 to March 2006 at Asan Medical Center. We evaluated incidence of stent thrombosis and major adverse cardiac events (MACE) including cardiac death, myocardial infarction (MI), and target vessel revascularization (TVR) during 3 years. We applied a classification of stent thrombosis set by the Academic Research Consortium (ARC). The outcome analysis was adjusted for differences in baseline characteristics. Results: Stent length (34.2짹15.2 mm vs. 21.1짹7.6 mm, p<0.001) was longer in DES group versus BMS group. Mean number of stent per lesion (1.3짹0.5 vs. 1.0짹0.2, p<0.001) were higher in DES group versus BMS group. The risk of MI (adjusted relative risk, 2.74; 95% CI, 0.43 to 17.36) and death (adjusted relative risk, 0.12; 95% CI, 0.003 to 4.90) was not different between two groups. The risk of TVR (adjusted relative risk, 18.8; 95% CI, 1.89 to 187.92) was significantly higher in patients treated with BMS. However, the adjusted risk of MACE (adjusted relative risk, 0.80; 95% CI, 0.20 to 3.13) was not statistically different with DES versus BMS up to 3 years of follow-up. During 3 year follow-up, there is no significant difference of the risk of stent thrombosis (set by any ARC criteria) between two groups (adjusted relative risk, 4.49; 95% CI, 0.47 to 42.19). Conclusions; Up to 3 years after primary stenting at AMI patients, the overall cumulative risk of stent thrombosis, death, or MI was not different between DES and BMS patients. Despite the significant reduction of TVR by DES, the overall MACE was not different as compared to BMS.