Background: Hemorheological abnormalities may lead to increased shear forces at the vascular endothelium via enhanced RBC aggregation and elevated local blood viscosity, thereby enhancing endothelial injury and promoting occlusive plaque formation. Among the several hemorheological parameters, erythrocyte sedimentation rate (ESR) is indirectly represented as red blood cell aggregation and whole blood viscosity. Additionally, ESR is readily available and relatively cheap parameter. In addition, marked alterations of rheological parameters could serve as a trigger for the rupture of a lipid-rich, unstable atherosclerotic lesion, thus leading to thrombus formation and the clinical symptoms of ACS. Therefore it seems very likely that local hemodynamic factors as well as hemorheological parameters may have critical roles in the pathophysiology. The purpose of present study hypothesized that there is a linkage between coronary artery disease and ESR as a hemorheological parameter. Subjects and Methods: From Jan. 2007, 652 stable patients with other risk factor including hypertension, hyperlipidemia, smoking, and diabetes without angina were included and clinically followed up (mean 2.5year). the patients who had acute or chronic inflammatory disease, or cancer were excluded. We have subdivided the patients without (G1) or with (G2) major adverse cardiac events (MACE) including cardiac death, newly developed angina, myocardial infarction, percutaneous coronary intervention or bypass graft. We have compared ESR, fibrinogen, hs-CRP, lipid profiles, and other basic clinical information between both groups. Results: The basic clinical characteristics including age, gender, and medication history were not significantly different between both groups. However, the frequency of diabetes was more frequent in G2. ESR, fibrinogen, and hs-CRP were significantly higher in G2. Interestingly, while there is no significant linear correlation between hs-CRP and fibrinogen, ESR was well correlated with fibrinogen (r²=0.451, p<0.01). And ESR was increased more during follow up period in G2. Conclusion: ESR as a hemorheological parameter representing RBC aggregation might be a good cardiovascular risk factor and have a good correlation with fibrinogen representing plasma viscosity indirectly. Our results thus suggest that selected, easily measurable rheological parameter (blood viscosity, RBC aggregation) could serve as surrogate markers for the presence and severity of atherosclerotic vascular diseases. Further, they suggest the merit of evaluating whether therapeutic interventions that normalize blood rheology reduce the incidence and/or progression of coronary artery disease.