Objective To investigate the clinical significance of myeloperoxidase (MPO) and paraoxonase (PON) in coronary heart disease (CHD) patients. Methods According to the results of selective coronary angiography, 300 hospitalized patients were divided into coronary heart disease group (n=240) and control group (n=60). Coronary heart disease patients were further divided into stable angina pectoris (SAP) group (n=60) and acute coronary syndrome (ACS) group (n=180) according to the clinical diagnosis; and were divided into group A, B and C according to the type of pathological changes. The lesions of coronary artery were graded by means of Gensini coronary score system. Meanwhile, the serum MPO were evaluated by colorimetry method and the PON-1 concentration level was determined by pheny acetate method. Results The level of MPO in CHD group was significantly higher [(52.23±13.92) vs (22.49±8.81) U/L, P＜0.01], PON level was significantly lower [(114.10±35.84) vs (139.40±39.42) mkat/L, P＜0.05] than that in the control group. In ACS group, MPO level was also significantly higher [(58.84±17.93) vs (36.52±8.21) U/L, P＜0.01], and the PON-1 level was significantly lower than that in the SAP group [(93.10±27.68) vs (111.97±33.42) mkat/L, P＜0.05]. When the coronary artery disease type and the severity of coronary artery disease became aggravated, the MPO level was gradually increased and the level of PON-1 was gradually decreased. Multiple linear regression analysis showed that MPO, PON-1, high density lipoproptein cholesterol (HDL-C) and low density lipoprotein cholesterol (LDL-C) concentrations were significantly correlated with the Gensini score of coronary lesions. Conclusion MPO, PON-1, HDL-C, LDL-C concentrations are significantly related with the Gensini score of coronary lesions. It may be involved in the development of atherosclerosis. MPO and PON-1 concentrations could be appropriate indicators to reflect the local inflammation of atherosclerotic plaque.