Backgroud: In the stent era, lesion length remains an important predictor for restenosis. Drug-eluting stents (DESs) have significantly reduced in-stent restenosis (ISR), but results in long lesions are still lacking. Therefore we investigated Impact of DES on the outcome of patients with diffuse long coronary lesion. Method: Between January 2004 to July 2005, 80 patients (94 lesions) with > 20-mm in lesion length who were treated with 1 or more DES and underwent follow-up coronary angiogram were selected for this study. The patients were divided into group 1 for those who had 21 to 35 mm in lesion length, group 2 with 36 to 50 mm in lesion length, and group 3 with > 51-mm in lesion length. Results: Mean follow-up duration was 9 months. At 6 months follow-up angiogram, 6.4% of lesions had binary ISR (5.0% group 1, 8.7% group 2 and 9.1% group 3). Clinical and angiographic data are in the below table. Lesion length was associated with increases in percent diameter stenosis and late lumen loss (per 15 mm of 6.9% and 0.21 mm). Conclusions: DESs implantation is considered safe and effective in the treatment of diffuse long lesion. However, lesion length was associated with increases in percent diameter stenosis and late lumen loss.