Aim To evaluate the relationship between inflammation and coagulation in the pathogenesis of atherosclerosis.Methods The expression and distribution of tissue factor(TF) and interleukin-18(IL-18) in the human normal coronary arteries and atherosclerotic plaques were studied using HE staining and immunohistochemistry.Results The expression of TF was not detected in the endothelial cells of normal arteries.But the endothelial cells overlying atherosclerotic plaques as early as in the type Ⅰlesions began to express TF(3/6) with 5/8 in the type Ⅱlesions.In the type Ⅲ～Ⅵ lesions almost all endothelial cells expressed TF.TF present in all macrophages and smooth muscle cells in all stages of atherosclerosis.There was some IL-18 positive areas in the specimens(14/40,35%),TF present in all the IL-18 positive areas.Conclusion The expression of TF is closely associated with the development of atherosclerosis.