Abstract: Objective To investigate the diversity of levels of plasma Cathepsin S and high sensitivity C-reactive protein(hs-CRP) in elderly patients with or without coronary artery disease.Methods Enzyme-linked immune sorbent assays(ELISA) was used to monitor the levels of plasma Cathepsin S(Cat S) and hs-CRP in 78 patients with acute ST-elevation myocardial infarction:72 with stable angina and 62 normal healthy people.Results The levels of Cat S and hs-CRP in patients,with acute ST-elevation myocardial infraction were higher than those in stable angina group,and control group was the lowest [(13.2±4.1) mg/L vs(5.0±1.0),(1.7±1.2) mg/L,all P<0.05;(30.6±3.5)μg/L vs(23.7±2.8),(18.2±3.8)μg/L,all P<0.05].Conclusion The levds of Cat S and hs-CRP in elderly patients with acute ST-segment elevation myocardial infarction and stable angina pectoris are high.The expression level of Cat S and hs-CRP is conrrelated with the severity of disease.Cat S and hs-CRP are involved in the formation and development of cardiovascular disease.