[Abstract] Objective: To investigate the relationship between levels of plasma lysophosphatidic acid(LPA) ,matrix metalloproteinase-9(MMP-9) and the severity of coronary artery disease in patients with acute coronary coronary heart disease(CHD) and to explore the potential clinical significance. Method: Patients with CHD were divided into four groups: acute myocardial infarction (AMI)group(n= 40) ; unstable angina pectoris (UAP)group (n=35);stable angina pectoris (SAP)group (n=35) ; and control group(n=30 )according to the state of illness and results of coronary angiography.The degree of coronary artery stenosis was determined by Gensini’s scores system, and the patients were redivided into four groups based on the interquartile of the Gensini’s scores:Ⅰgroup（0 ～ 7 scores）(n=35), Ⅱgroup（7 ～ 26 scores）(n=36), Ⅲgroup（26 ～ 46 scores）(n=26) and Ⅳgroup(＞46 scores)(n=43). Plasma LPA and MMP-9 were determined by inorganic phosphours quantitative method and enzyme-linked immunosorbent assay. Result: LPA and MMP-9 levels and Gensini's scores were significantly higher in each group of patients with CHD compated to the control group（P<0.01）; in AMI group were higher than in UAP group and in SAPgroup（P<0.01）;and in UAP group were higher than in SAP group（P<0.01）; There were statistically significant differences of LPA and MMP-9 levels between eacher other group among in the four groups based on the interquartile of he Gensini's scores（P<0.01）. LPA level was positive correlated with MMP-9 (r=0.22，p<0.05). Conclusion: Plasma LPA and MMP-9 levels were significant higher in in patients with CHD, which were closely related to the severity of coronary artery disease and the degree of coronary artery stenosis. Key words: coronary artery disease；1ysophosphatidic acid；Matrix metalloproteinase-9 [Abstract] Objective: To investigate the relationship between levels of plasma lysophosphatidic acid(LPA) ,matrix metalloproteinase-9(MMP-9) and the severity of c