<正> Objective: To investigate the changes of the plasma level of MMP-9 （ Matrix Metalloproteinase-9

MMP-9） in the patients with abdominal aortic aneurysms （ AAAs） before and after the treatment

and evaluate the significance of MMP-9 in the pathogenesis of AAAs. Methods: Blood samples of 35 patients with AAAs and 10 patients with the arterial occlusive diseases （ AODs）

which enrolled into the Vascular Surgery Center of Colonge University Hospital from February to August of 2002

were collected before and one month after surgical repair or less-invasive endovascu-lar exclusion. The plasma concentrations of MMP-9 of all the collected samples were measured by means of enzyme-linked immunosorbent assay （ ELISA）

and compared between the two groups patients at different time point. Results: The mean plasma concentration of MMP-9 of AAAs was significantly higher than that of AODs prior to treatment [（90.3±9.1） ng/ml vs （23. 6±7. 3） ng/ml

P < 0. 05 ]

and no apparent difference was showed in the patients w