Objective:To analyze the differences of the levels of human tissue kallikrein(KS)-binding protein in plasma of coronary heart disease(CAD)patients,and evaluate the correlation between KS and the severity of coronary artery stenosis. Methods:A total of 151 patients with coronary angiography were enrolled in this study. Their clinical data and results of coronary angiography were collected. Plasma KS were measured by ELISA. Patients were stratified into four groups according to the results of coronary angiography(single coronary artery stenosis,double coronary artery stenosis,triple coronaryartery stenosis and controls)and four groups according to Gensini score [A group(0),B group(>0~≤20),C group (>20~≤40),and D group (>40~-艽160)] at the second step. KS levels were compared between different groups and correlation analysis was made between KS and Gensini score. Results:①In the four groups which were stratified according to the results of coronary angiography,the levels of KS in control (95.35 ± 32)μg/mL were significantly higher compared with single coronary artery stenosis(78.19 ± 25.27)μg/mL,double coronary artery stenosis (66.19 ± 25.93)μg/mL,and triple coronary artery stenosis (51.84 ± 23.26)μg/mL. There were statistically significant differences among the four groups(P < 0.001). ②In the four groups which were stratified according to Gensini score,the levels of KS were(101.66 ± 36.50)μg/mL,(77.73 ± 25.13)μg/mL,(61.58 ± 23.06)μg/mL,and(53.80 ± 23.92)μg/mL,respectively. There were statistically significant differences among the four groups(P < 0.001). ③Futhermore,there was a significant negative correlation between plasma KS levels and the Gensini score(r=-0.371,P < 0.001). Conclusions:The plasma KS levels were remarkable lower in the groups of CAD compared with controls. It indicates a novel role of KS in the progress of coronary atherosclerosis and the development of CAD.