The expression and significance of osteopontin (OPN) and NF-kappa B 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-kappa B P65 (NF-kappa B 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-kappa B P65. Immunohistochemical results showed that the expression of OPN, NF-kappa B 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-kappa B P65, uPA, MMP-2 and MMP-9 and between the expression of NF-kappa B P65 and that of uPA, MMP-2, MMP-9 (P < 0.05). Western blotting demonstrated that OPN and NF-kappa B 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-kappa B P65 between AAA and TAA specimens (P > 0.05). It was concluded that OPN and NF-kappa B P65 were involved in the pathogenesis of TAA and AAA. OPN can up-regulate the expression of MMP and uPA via NF-kappa B signaling pathway thereby accelerating the degradation of extracellular matrix and playing an important role in the pathogenesis and development of TAA and AAA.