Background Thin-strut stents have been reported to have favorable effects on restenosis possibly due to lesser vascular injury compared to conventional bare metal stents. The objective of this multicenter study was to compare DRIVER stent, a thin-strut cobalt-based alloyed stent(strut thickness 0.090 mm) with S7 stent, a stainless steel stent with same stent design(strut thickness 0.127 mm) in the clinical and angiographic outcomes. Methods Between April 2002 and March 2004, DRIVER coronary stents were implanted in 212 patients(222 lesions) and S7 coronary stents in 160 patients(167 lesions) respectively. We compared clinical and angiographic outcomes between the two different stent groups. The primary end point was the incidence of MACE(major adverse cardiac events; Death, myocardial infarction(MI) and target-vessel revascularization(TLR). The secondary end point was angiographic restenosis(���50% diameter stenosis at follow-up angiography). Results Both groups have similar baseline clinical and angiographic characteristics. The one-year MACE rate was 6.7% in DRIVER stent group and 11.2% in S7 stent group(p=0.14). No significant difference was observed in the cumulative cardiac event-free survival rate using Kaplan-Meier Method(log rank, p=0.32). The incidence of angiographic restenosis was 28.8% in DRIVER group and 39.6% in S7 group (p=0.30). Although there was no significant difference in restenosis rates, the late loss in Driver stent group was lesser than S7 stent group. Preliminary datas were as below. Conclusion There was no significant difference in clinical outcomes and angiographic restenosis rates between the two stents with same design, but different material and strut thickness. However, thin-strut cobalt alloyed stents showed the tendency toward lower MACE and restenosis rates and caused significantly lesser late loss compared to conventional stents.