Background: Tissue factor binds coagulation factor VII, leading to activation of both intrinsic and extrinsic blood coagulation cascades, and plays an important role in cardiovascular disease including acute coronary syndrome. In vitro experiments showed that IL-6,8 & TNF-慣 induced tissue factor expression. The aim of this study is to evaluate the effect of simvastatin on plasma tissue factor expression & the concentration of the regulatory cytokines in hypercholesterolemic patients. Method: The LDL-C level of the hypercholesterolemic patients in this study was above 130mg/dl even after 4-weeks diet therapy. The plasma tissue factor expression, IL-6, 8, & TNF-慣 level were determined with ELISA kit before and after 4-weeks simvastatin (20mg/d) therapy (N=20). Results: There were significant improvements in the lipid profiles after simvastatin therapy (total cholesterol; 260짹24 to 182짹26mg/dl: p<0.05, LDL-C; 180짹32 to 110짹23mg/dl: p<0.05). Simvastatin significantly decreased plasma tissue factor expression (164짹121 to 94짹54 pg/ml; p<0.05). Furthermore, simvastatin significantly lowered the plasma level of IL-6, 8 &TNF-慣 by 57%, 43%, 61%, respectively (p<0.05). Conclusion: These findings confirm the hypothesis that statin decreases plasma tissue factor expression by suppressing the regulatory cytokines such as IL-6,8 and TNF-慣 in hypercholesterolemic patients, and that suppression of tissue factor expression leading to decreased thrombogenecity is one of the action mechanism of statin to prevent cardiovascular events.