Objective: Genetic factors, in addition to oxidative stress factors, have been implicated in the development of chronic obstructive pulmonary disease (COPD). Multi-drug resistant-1 (MDR-1) is a gene located on chromosome 7 and the products of this gene protect lung tissue from oxidative stress. We searched the frequency of MDR-1 gene C/T polymorphism in patients with COPD and aimed to explain the association between MDR-1 gene and COPD development. Methods: 47 patients with COPD and 64 healthy control participants were placed in this study. DNAs were extracted from blood samples and MDR-1 amplification of DNA was performed using polymerase chain reaction and enzyme digestion techniques. Results: The frequencies of MDR-1 genotypes were found 17.0% for CC, 51.1% for CT and 31.9% for TT in the COPD group and 39.1% for CC, 53.1% for CT and 7.8% for TT in the control group. The distribution of MDR-1 gene C alleles were found 32.3% in COPD group and 67.7% in control group; T alleles were found 55.1% in COPD group and 44.9% in control group. There was statistically significant difference between the groups for genotype and allele frequency of MDR-1 gene (P = 0.001). Conclusion: TT genotype of MDR-1 gene was significantly more frequent in COPD patients. MDR-1 gene C/T polymorphism may play a role in COPD development.