Objective To study the expression level of interleukin (IL)-22 in the peripheral blood of patients with ankylosing spondylitis and its clinical significance.Methods The mRNA level of IL-22 in the peripheral blood was measured by real-time quantitative polymerase chain reaction,and the plasma level of IL-22 was measured by enzyme linked immunosorbent assay in 30 patients with ankylosing spondylitis and 30 normal controls.Results The mRNA level of IL-22 in the peripheral blood and the plasma level of IL-22 in patients with ankylosing spondylitis were statistically higher than those in normal controls [1.82 ± 0.79 vs.1.31 ± 0.63 and (47.08 ± 17.25) ng/L vs.(30.47 ± 11.24) ng/L,P ＜ 0.05].Conclusion The level of IL-22 in the peripheral blood of patients with ankylosing spondylitis increases,and IL-22 may participate in the occurrence of ankylosing spondylitis.