Objective To determine the plasma urolensin Ⅱ(UⅡ) levels in various types of coronary heart disease and to clarify how the plasma UⅡ levels correlate with the clinical presentation, extent and severity of coronary artery atherosclerosis (CAD). Methods: One hundred and three aged patients undergoing elective diagnostic coronary angiography for proven or clinical suspected coronary heart disease were enrolled in this study. The extent and severity of coronary artery disease were evaluated by vessel score and Gensini score, respectively. Plasma UⅡ levels were measured by radioimmunoassay. Results: The plasma UⅡ levels in the patients with modest to severe coronary stenosis (3.03±0.34 pg/ml, 1.83±0.67 pg/ml) were significantly lower than that in subjects with normal coronary artery (4.80±1.11 pg/ml, P＜0.001). The plasma UⅡ levels in patients with coronary heart disease were also significantly lower than that in patients with insignificant coronary stenosis (P ＜ 0.001). Compared to patients with stable angina pectoris, plasma UⅡ levels in patients with acute coronary syndrome were significantly decreased (1.89±0.51 pg/ml vs 2.42±0.77 pg/ml, P＜ 0.001). Plasma UⅡ levels were found to be negatively correlated with the severity of coronary artery stenosis (r = -0.488, P＜0.001), as well as the vessel score (r = -0.408, P＜0.05) in the patients with CAD. Conclusion: Significant inverse correlations exist between the plasma UⅡ levels, and the extent and severity of coronary artery stenosis. These findings suggest that plasma UⅡ contribute to the development and progression of coronary artery stenosis, and may be a novel marker to predict clinical types, as well as the extent and severity of coronary artery disease in the patients.