The expression and significance of osteopontin (OPN) and NF-κB in patients with thoracic aortic aneurysm (TAA) and abdominal aortic aneurysm (AAA) were investigated.Thirteen TAA specimens,20 AAA specimens and 6 normal aortic specimens were collected.The expression of OPN,nuclear factor-κB P65 (NF-κB P65),urokinase plasminogen activator (uPA),matrix metalloproteinase-2 (MMP-2) and matrix metalloproteinase-9 (MMP-9) were detected by using immunohistochemistry and Western blotting was employed to determine the expression of OPN and NF-κB P65.Immunohistochemical results showed that the expression of OPN,NF-κB P65,uPA,MMP-2 and MMP-9 was positive in all TAA and AAA specimens and negative in normal specimens,with the difference being statistically significant (P＜0.05).There was no difference in the expression between TAA and AAA specimens (P＞0.05).Correlation analysis revealed that there existed a positive correlation between the expression of OPN and that of NF-κB P65,uPA,MMP-2 and MMP-9 and between the expression of NF-κB P65 and that of uPA,MMP-2,MMP-9 (P＜0.05).Western blotting demonstrated that OPN and NF-κB P65 were positive in AAA and TAA specimens,and negative in normal specimens with the differences being statistically significant (P＜0.05).There were no statistically significant differences in the expression of OPN and NF-κB P65 between AAA and TAA specimens (P＞0.05).It was concluded that OPN and NF-κB P65 were involved in the pathogenesis of TAA and AAA.OPN can up-regulate the expression of MMP and uPA via NF-κB signaling pathway thereby accelerating the degradation of extracellular matrix and playing an important role in the pathogenesis and development of TAA and AAA.