Backgrounds: It has been known that the vascualar endothelial damage, inflammation and neointimal proliferation play a cental role of restenosis after coronary stenting. Neointimal smooth muscle cell proliferation and inflammatory response can be more activated in younger ages, but there were few reports about restenosis rate based on patient's age. We presumed that restenosis rate maybe higher in younger patients after coronary artery stent implantation and evaluated the in-stent restenosis rate based on the age and other risk factors. Methods: 397 patients (mean ages 57짹10 yrs, 288 male, 109 female, 127 diabetes mellitus) who had implanted conventional bare metal stents were evaluated. The follow-up coronary angiography was assessed from 4months to 12months after initial PCI: the time after the period of maximal neointimal proliferation state (220짹51days). We compared patient's age and other conventional risk factors (diabetes, hypertension, smoking, sex, stent diameter, stent length) in the angiographic restenosis group (n=145) and patent stent group (n=252) by multivariate analysis. Results: Among the risk factors, smoking history (OR: 1.748, p=0.008) showed significant correlation with restenosis rate and stent diameter (OR: 0.391, p=0.001) showed reverse correlation. However there were no correlation between restenosis rate and sex, hyperlipidemia, hypertension, and stent length. There was no significant correlation (p=0.336) between patient's age and restenosis rate and showed no significant difference between each age decades by multivariate analysis (p=0.28,0.61,0.86,0.96,0.75). Conclusions: Younger patient's age did not showed significant correlation between in-stent restenosis rate after stenting. But there were trend of high restenosis rate in 3rd and 4th decades. Smoking and stent diameter may be more important risk factor for restenosis. Therefore, we have to consider drug eluting stent insertion in young patient's with other conventional risk factor of restenosis.