Abstract: Objective: DNA repair plays important roles in maintaining genomic integrity and prevention of carcinogenesis. Base excision repair (BER) is one type of DNA repair that operates on small lesions. XRCC1 (X-ray repair cross complementing group1) protein is an important component of BER. The aim of this study was to evaluate the association between the Pro206Pro and Gln632Gln polymorphisms of DNA repair gene XRCC1 and the prevalence of lung cancer in the Chinese population. Methods: A hospital-based case control study was designed that consisted of 247 cases of lung cancer and 253 cancer-free control subjects matched in age (± 3 years), gender and ethnicity. All subjects were ethnic Han Chinese and were unrelated. PCR-RFLP was used for genotyping. Results: Carriers of the variant G-allele of Pro206Pro were at significantly increased risk of developing lung cancer(adjusted OR=1.96, 95% CI=1.26-3.06, P=0.003, adjusted for smoking duration). No significant factors were associated with the Gln632Gln XRCC1 polymorphism. Interactions between genotype and smoking history were not seen in stratified analysis. The two SNPs were in strong linkage disequilibrium (D'=0.807, P= 3.1e-115). Haplotype distributions were significantly different between lung cancer cases and the controls(P=2.25e-06). A haplotype of Pro206Pro(A)-Gln632Gln(G) was associated with decreased risk of lung cancer(OR=0.66, 95% CI=0.45-0.96, P=0.03) and a haplotype of Pro206Pro(G)-Gln632Gln(G) was associated with significantly increased risk of lung cancer (OR=16.09, 95% CI=3.89-66.53, P=3.09e07). This finding indicates that the interaction between these genes is closely related to disease susceptibility. Conclusion: Polymorphisms in the DNA repair gene XRCC1 may play an important role in the occurrence of lung cancer in the Chinese population.