Background Interleukin-13 (IL-13) has been implicated to be responsible for recruitment of inflammatory cells from the blood to the lung,regulation of matrix metalloproteinase and induction of mucin production and secretion in chronic obstructive pulmonary disease (COPD).We determined plasma IL-13 levels in patients with COPD and investigated its association with common polymorphisms of IL-13 gene in a case-control study.Methods We genotyped 160 cases and 175 control subjects in a local hospital using Mass-ArrayTM Technology Platform then tested the association of four SNPs in IL-13 (rs1295685,rs1800925,rs1881457,rs20541) with COPD,and then determined plasma IL-13 levels in patients with COPD and controls.Results Association was found between IL-13 gene SNPs (rs20541 and rs1800925) and an increased risk of COPD.By linkage disequilibrium (LD) analysis,two blocks (rs1881457 and rs1800925; rs20541 and rs1295685) were found.The risk of COPD was found associated with the IL-13 gene polymorphism among south Chinese Han population.Plasma IL-13 level was increased in COPD patients compared with controls.Conclusions The polymorphism of the IL-13 gene is associated with an increased risk of COPD in south Chinese Han population.Plasma IL-13 levels were found elevated in patients with COPD.