Background : Oxidative stress might be a role in atherosclerosis and intake of antioxidant appears to be protective and modify neointimal formation. Antioxidant nutrient, 慣-lipoic acid, inhibits adhesion molecule expression and monocyte adhesion and prevents oxidative lipid damage. We investigated the role of 慣-lipoic acid in the change of the serum C-reactive protein level and preventing in-stent restenosis after coronary bare metal stenting. Methods : Total 81 patients with coronary artery disease have been enrolled in the study and randomly assigned to control or thioctic acid group(慣-lipoic acid 600mg). We performed follow up coronary angiography in 24 patients of control group and 25 patients of antioxidant group after 6 month of coronary bare metal stent implantation. We counted the stenotic lesions more than 50% of implanted stent lumen as a restenosis by quantitative coronary angiography. C-reative protein measurement were performed on Hitachi 7600-110짰 autoanalysis(Hitachi Co. Tokyo. Japan) with turbidimetric immunoassay. Results : Reference diameter, stent diameter and length, post minimal luminal diameter were not different between two groups. Baseline clinical characteristics, such as diabetes mellitus, hypertension, blood chemistry, lipid profiles were not different between two groups. C-reactive protein level in thioctic acid group was significantly decreased after thioctic acid supplementation(0.09짹0.03 mg/dL vs 0.37짹0.34 mg/dL of C-reactive protein before supplementation, p<0.05). At follow up coronary angiography, the restenosis rate was 34 % versus 27 % with an associated late loss of 0.86짹0.64 versus 0.66짹0.36 mm (p=NS) for thioctic acid and control group. Conclusions : Thioctic acid (慣-Lipoic acid) supplementation significantly decreased the serum C-reactive protein level but could not prevent in-stent restenosis after coronary bare metal stent implantation.