We investigated the changes of matrix metalloproteinase (MMP) -9 in the peripheral blood samples of patients undergoing endovascular aneurysm repair (EVAR) for abdominal aortic aneurysms (AAAs), and the effect of azelnidipine on plasma MMP-9 levels in those patients. Levels of MMP-9 were measured in 22 patients who underwent EVAR for AAAs, and results were compared between a group receiving 16 mg azelnidipine daily (n=12) and a control group without azelnidipine (n=10). Measurements were taken preoperatively, and at 1 month and 3 months, postoperatively. Patients without endoleaks after EVAR showed a significant decrease in mean plasma MMP-9 levels (preoperative value: 39.5±14.3 ng/mL, after 1 month: 25.0±12.6, after 3 months: 28.2±10.2 ng/mL; P=0.004). In contrast, no significant decreases in mean plasma MMP-9 levels were observed in the patients with endoleaks after EVAR (preoperative value: 37.5±9.0 ng/mL, after 1 month: 26.8±8.4, after 3 months: 38.5±15.7 ng/mL; P=0.219). Moreover, among patients without endoleaks, those receiving azelnidipine showed a significantly greater decrease in the mean plasma MMP-9 levels for 3 months postoperatively (preoperative value: 47.7±13.2 ng/mL, after 1 month: 26.6±12.8, after 3 months: 26.1±11.4 ng/mL; P‹0.001) compared with the control group without endoleaks (preoperative value: 31.3±10.5 ng/mL, after 1 month: 33.4±12.1, after 3 months: 30.3±9.1 ng/mL; P=0.792). These results showed that azelnidipine treatment in patients without endoleak after EVAR was associated with a significant decrease in mean plasma MMP-9 levels for 3 months postoperatively.