Interleukin-13 (IL13) -1055 polymorphism has been implicated in the development of chronic obstructive pulmonary disease (COPD) in various studies with conflicting results. The aims of this study are to investigate whether IL13 -1055 polymorphism is associated with the development of COPD in Taiwanese smokers; and to determine if IL13 -1055 polymorphism is associated with the severity of COPD. A case-control study was conducted on COPD patients (n = 85) and healthy smoker (n = 72). Genomic DNA was extracted for genotyping of IL13 sequencing and serum IL-13 was measured using by enzyme-linked immunosorbent assay (ELISA). After adjusting smoking index and age confounding, the T-allelic frequencies of the IL13 -1055 gene polymorphisms in COPD group are significantly higher than those in control group (18.8% versus 1.4%; P < .001; odds ratio [OR] = 29.3; 95% confidence interval [CI]: 5.9-145.3); and the frequencies of CT/TT genotypes in COPD group are significantly higher than those in control group (27.1% versus 2.8%; P < .001; OR = 20.0; 95% CI: 3.9-100.8). In COPD patients, stepwise linear regression shows IL13 -1055 T allele is the independent factor associated with forced expiratory volume in 1 second (P = .007), but not associated with serum IL-13. In conclusion, IL13 -1055 T allele is associated with the development and severity of COPD in Taiwanese smokers.