Background Drug-eluting stents (DES) have provided a significant innovation for preventing in-stent restenosis. Small vessel diameter is a risk factor of in-stent restenosis following percutaneous coronary intervention (PCI). In this study, we evaluated the efficacy of PCI with DES in patients (pts) with small coronary lesions. Methods From Sep 2004 to Dec 2006, a total of 735 pts (1064 lesions) with coronary artery lesions were treated with DES (Cypher or Taxus). The enrolled pts were divided into two groups: Small vessel group (���2.5mm) and Non-small vessel group (>2.5mm). The procedural, angiographic and clinical outcomes were compared up to 6 months. Results In this study, 176 pts (200 lesions) were included in small vessel group and 559 pts (864 lesions) in Non-small vessel group. The clinical and angiographic baseline characteristics were similar between the two groups. The percentage of procedure success was high and there was no difference between the two groups (97.9% vs. 97.6%, p=0.820). At 6 month, although the incidence of binary restenosis was higher in the small vessel group, but the clinical outcomes were not different between the two groups (Table). At 6-month follow up, the survival and freedom from MACEs was similar between the two groups (96.5% vs. 95.8%, p=0.549). Conclusion The procedural success, survival and freedom from MACEs were high in pts who had small coronary lesions undergoing PCI with DES up to mid-term follow up despite the incidence of binary restenosis was higher.