Abstract: AIM:To compare the imaging characteristics of coronary artery plaques between patients with stable angina（SA） and patients with unstable angina（UA） by qualitative and quantitative analysis of the plaques by intravascular ultrasound（IVUS）.METHODS:All patients（37 SA patients vs.34 UA patients） underwent coronary angiography and IVUS in this study.Characteristics of atherosclerotic plaques were analyzed,and external elastic membrane area（EEMA）,lumen cross-sectional area CSA（LA）,plaque cross-sectional CSA（PA）,plaque burden（PA/EEMA） and remodeling index of coronary artery were measured.All indices were compared between groups.RESULTS:The average number of soft plaques in UA patients was higher than that in SA patients（P<0.05）,whereas the number of calcified plaques was similar in the two groups.Quantitative analysis showed no significant difference in EEMA,but significant difference was found in the plaque burden（P<0.01） between groups.Positive remodeling was observed in UA patients,whereas negative remodeling was observed in SA patients.CONCLUSION:Some differences exist in the properties of coronary artery plaques and the manner of vascular remodeling between patients with SA and patients with UA.IVUS can effectively display the characteristics of coronary artery lesions.