Objectives: This study compared clinical outcome and cost-effectiveness between cobalt chromium based bare metal stent (Driver) and the zotarolimus-eluting stent (Endeavor), sharing the same bare metal strut platform, in patients who underwent single-vessel PCI in large coronary arteries . Methods : A total of 142 patients with acute coronary syndrome who underwent single-vessel PCI in large coronary arteries (>=3.5mm) between 2005 and 2007 were divided into two groups: group I: patients who received Driver stent, N=54 and group II: patients who underwent Endeavor stent implantation, N=88. Clinical outcomes after 12 months were compared between groups. Results: Baseline clinical and procedural characteristics were similar. Stent diameter was significantly greater in group I (group I: 3.81짹0.34mm, group II: 3.61짹0.21mm, p < 0.001), but stent length was not significantly different (group I: 21.39짹5.24mm, group II: 22.94짹5.36mm, p = 0.09). After 12 month follow up, the MACE occurred in 18.5% of patients with group I (N=10: one cardiac death, one AMI, and eight TLRs) and 15.9% of patients with group II (N=14: six cardiac death, one AMI, and seven TLRs), but there was no statistical difference between the two groups. Total costs were higher in group II than group I. Conclusion: Clinical outcomes of cobalt chromium based BMS were comparable with those of zotarolimus-eluting stents(ZES) in patients who underwent single-vessel PCI in large coronary arteries. And the use of ZES is less cost effective than the use of cobalt chromium based BMS in patients with single-vessel disease in large coronary arteries.