Background : The treatment of diffuse coronary artery lesions in one of the most challenging problems for interventional cardiologist. Although coronary stenting has improved the procedure success rate, high restenosis rate is remaining problem. The objective of this study is to compare the efficacy of DES and bare metal stent(BMS) in treating diffuse (>30mm) coronary lesions. Method : We analyzed 104 patients with diffuse coronary artery lesion who implanted DES(n=60, 43 males, mean ages 59.6짹9.6 years) or BMS(n=44, 31 males, mean ages 60.2짹10.9 years). Clinical follow-up was performed at one month and six months and, in case of DES, we performed follow-up angiography at nine months. Results : Baseline clnical and angiographic characteristics in both group were similar. Angiographic success rate were 100% in both groups. A follow-up angiography was performed in 30 patients(28.8%) including 14 patients in BMS group. Most follow-up angiography will be performed within next two months. Although there was no significant statistical difference, the rate of restenosis trend to lower in DES group(4/16, 25.0%) than in BMS group(8/14, 57.1%)(p=0.073). And interestingly, type of restenosis was different between both groups. In DES group, incidence of edge restenosis was higher than in BMS group(3/4, 75.0% vs 1/8, 12.5%, p=0.030), No patient who showed acute or subacute thrombotic stent occlusion was observed at both group. The incidence of MACE at one month (1/59, 1.7% vs 1/44, 2.3%, p=0.824) and at six month(3/60, 5.0% vs 4/40, 10.0%, p=0.411) was not different between both groups. Conclusion : Although, in diffuse coronary lesion, PCI with DES showed trending to lower restenosis rate, the incidence of MACE was not different between both groups during follow-up period.