Background: Low molecular weight heparin has shown to be more effective than unfractionated heparin (UFH) for treatment of patient with acute coronary syndrome. However, few data are available regarding safety and efficacy during percutaneous coronary intervention (PCI) in patients with coronary artery disease. Methods: In this prospective, a total of 244 patients, including 162 enoxaparin (1mg per kilogram of body weight) patients and 82 UFH (100 unit per kilogram of body weight) patients were randomly assigned during PCI. The incidence of major or minor bleeding, and time to sheath removal were evaluated. The incidence of major adverse cardiac events (MACE: cardiac death, non-fatal myocardial infarction,Target vessel revascularization) at one month were also evaluated. Results: Baseline patient demographics were similar between the 2 groups. There was no evidence of major bleeding in neither group. Minor bleeding was occurred in 3.7 % of both enoxaparin and UFH groups. However, the time to sheath removal after PCI was significantly earlier in enoxaparin group than UFH group (258.5짹 50.6 minutes vs. 400.5짹78.6 minutes,p<0.0001). The incidence of MACE was similar between the 2 groups. Conclusion: Enoxaparin may be safe and convenient as anticoagulant during PCI without increasing MACE compared to UFH, suggesting as alternative modality to UFH during PCI.