To investigate the roles of the plasma vascular endothelial growth factor (VEGF) level and VEGF gene polymorphisms in ankylosing spondylitis (AS) susceptibility. The plasma VEGF level was measured using an enzyme-linked immunosorbent assay. The VEGF rs2010963 G/C gene polymorphism was analyzed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Our data indicated that the average plasma VEGF concentration in the AS patients was markedly higher than in the controls. Stratification analysis indicated a significant correlation between an elevated plasma VEGF level in AS patients and sex, but not age, HLA-B27, C-reactive protein (CRP), or grade of the sacroiliac joint. We also found that VEGF rs2010963 G/C was associated with a decreased risk of AS. Significant differences were found between the VEGF rs2010963 G/C genotypes and elevated plasma level in AS patients when compared with the controls. However, we did not find a significant association between the plasma VEGF level and different rs2010963 G/C genotypes in the AS patients or controls. To sum up, serum VEGF levels are significantly associated with the inflammatory process of AS. This study suggests that VEGF is involved in the immunological or inflammatory process of AS. (C) 2016 European Federation of Immunological Societies. Published by Elsevier B.V. All rights reserved.