Objective:To study the relation of serum matrix metalloproteinase-9 (MMP-9) and tissue inhibitor of metalloproteinase-1(TIMP-1) with carotid artery atherosclerosis in elderly patients with cerebral infarction. Methods:Two hundred and sixty patients with cerebral infarction were divided into normal intimated thickness(IMT) group(n = 24),increased IMT group(n = 62),stable plaque group (n = 110) and unstable plaque group(n = 64). Their IMT and carotid plaques were detected by high resolution B mode ultrasonography. And their serum levels of biochemical indicators,MMP-9 and TIMP-1,were measured and compared. Results:The serum MMP-9 and TIMP-1 levels increased gradually in the 4 groups and were higher in the unstable plaque group than in the other three groups (P < 0.01). Logistic regression analysis showed that the arotid artery atherosclerosis was positively correlated with the body mass index (BMI),systolic blood pressure (SBP),triglycerides (TG),and lgMMP-9 of patients with cerebral infarction. And the stability of carotid plaque was positively correlated with the BMI,TG and lgMMP-9. Conclusion:Serum MMP-9 and TIMP-1 levels are closely related with stability of carotid plaque in aged patients with cerebral infarction.