OBJECTIVE A-463 bp G/A polymorphism is located in the promoter region of myeloperoxidase (MPO) gene was found to be associated with lung cancer susceptibility; however, this association in Chinese population remained unclear. The aim of this study was designed to explore this association in Chinese population. METHODS MPO genotypes in 98 cases of primary lung cancer and 112 persons of healthy control were detected using PCR-restriction fragment length polymorphism assay(PCR-RFLP) in a case-control molecular epidemiology study. The association between this gene polymorphism and the risk of lung cancer in Chinese population was examined through comparing odds ratio(OR) and 95% confidence interval(CI) between two groups. RESULTS In healthy control group, the frequencies of persons carrying G/G, G/A, and A/A genotypes were 47.3%, 42.9%, and 9.8%, respectively. In cancer group, the frequencies of the persons carrying above three genotypes were 63.3%, 33.7%, and 3.0%, respectively. There was no significant difference of the frequencies of heterozygote G/A between two groups (P >0.05). However, The A/A genotype was found significantly higher in cancer group than that in healthy control group(P< 0.025). The risk of lung cancer for person carrying at least one A allele was only 52% of the persons carrying G/G genotype (95% CI 0.29-0.93). In smoking population, allele A showed to be a significant protective factor (OR=0.41,P< 0.025), while such protective role was not observed in non-smoking group(P >0.25). CONCLUSIONS MPO gene polymorphism was associated with susceptibility of lung cancer in Chinese population. The risk of lung cancer was decreased in the persons carrying allele A.