Objective: Percutaneous coronary intervention (PCI) with drug-eluting stents (DES) may be useful in patients with acute myocardial infarction (AMI), but DES seem less effective in patients with diabetes mellitus (DM). This study was aimed to to evaluate the efficacy of DES in patients who underwent PCI due to AMI with DM in a real-world setting. METHODS AND RESULTS: On-line registry of 2,432 patients with AMI and DM at the web site(www.kamir.or.kr) has been performed in 41 primary PCI centers in Korea and between November 2005 and September 2006. Total 2,023 surviving patients who had been implanted with either Cypher or Taxus stents were enrolled for analysis during a 12-month clinical follow-up. There were 2 groups: group I [1,230 patients: sirolimus-eluting stent (SES, Cypher)], group II [793 patients: paclitaxel-eluting stent (PES,Taxus)]. There were no significant differences in clinical and angiographic characteristics between the two groups. At 1 month follow up, the incidence of MACE was not significantly different between the two groups. At 6 months, the incidence of MACE was was significantly higher in group II (group I:II= 45(3.7%): 49(6.2%), p=0.013). And at 12 months follow up, the incidence of MACE was not significantly different between the two groups. There were 8 cases of stent thrombosis(group I:II= 5(0.41%): 3(0.37%), p=0.921), and all stent thrombosis case were subacute stent thrombosis. The stent type, length, number, lesion complexity were not significant for the incidence of MACE or stent thrombosis after adjustment. CONCLUSION: SES implantation significantly reduced the 6 months risks of MACE compared with PES implantation in diabetic patients in Korea Acute Myocardial Infarction Registry (KAMIR). Further long term follow up of MACE and stent thrombosis should be needed.