Background: Compared with bare-metal stent, drug-eluting stent (DES) delayed endothelial regrowth, suggesting the possibility of ���late catch-up��� phenomenon. However, there is paucity of data regarding the long-term angiographic or intravascular ultrasound (IVUS) outcomes after DES implantation. Methods: This prospective observational study included de novo coronary lesions treated with DES between Mar 2003 and Feb 2006. Inclusion criteria were lesions which received the first angiographic follow-up at 6-9 months after the procedure and the second at 2 years. Exclusion criteria were patients who were older than 75 years, or had limited life expectancy or serious comorbid disease, and lesions which were in-stent restenosis, graft stenosis, or bifurcation stenosis stented in the side branch at the index procedure, or received target vessel revascularization due to restenosis or stent thrombosis before the second angiographic follow-up. The primary end point was the serial changes of luminal diameter at the post-procedure, the first, and second angiographic follow-ups. A comparison of serial quantitative angiographic analysis will be performed using the multiple-comparison procedures. In addition, multivariable analysis models will be created to identify factors to be associated with progressive luminal narrowing at the different time periods. All analysis will be basically performed per a lesion basis. Results: Serial angiographic analyses at 6 months and 2 years are being performed for 834 lesions treated with sirolimus-eluting stents (75%) or pacliaxel-eluting stents (25%) from the eligible patients who met the inclusion and exclusion criteria, and gave a written informed consent. In addition, serial IVUS analyses at the two stages of follow-up are also being performed in another IVUS cohort of 150 lesions. Final analytic results will be available in September, 2008. Conclusion: This study of DES-FU will provide very important information regarding the long-term serial changes of stented segment after DES implantation.