Background/Aim: Nijmegen breakage syndrome 1 (NBS1) is a component of MRE11/RAD50/NBS1 complex (MRN) that plays a critical role in the cellular response to DNA damage and maintenance of chromosomal integrity. Failure in DNA damage response affects the level of cell survival, increases the frequency of gene mutation or chromosomal instability and other cellular phenotypic abnormalities, which are the important mechanisms of carcinogenesis. However, the contribution of variant NBS1 genotypes to lung cancer is not known. The current study aimed to evaluate the contribution of the common variant NBS1 Glu185Gln (rs1805794, E185Q) genotypes to the risk of lung cancer. Materials and Methods: The contributions of the NBS1 Glu185Gln genotypes to lung cancer risk were investigated among 358 patients with lung cancer and 716 age- and gender-matched healthy controls by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). Results: GG, CG and CC NBS1 Glu185Gln genotype percentages were 45.2%, 43.9% and 10.9% in the patient group and 46.1%, 45.1% and 8.8% in the non-cancer control group, respectively (p for trend=0.5423). Analysis of allelic frequency distributions showed that the C allele of NBS1 Glu185Gln did not increase lung cancer susceptibility (p=0.4916). Interestingly, the CC genotypes at NBS1 Glu185Gln enhanced the risk of lung cancer among the males adjusted odds ratio (aOR)=1.85, 95% confidence interval (CI)=1.12-2.83 and among the smokers (aOR=1.76, 95% CI=1.09-2.64) but not among the females and non-smokers. Conclusion: The CC genotype of NBS1 Glu185Gln may increase lung cancer risk only for males and smokers and may serve as a practical marker for early detective and predictive purposes of lung cancer.