The ERCC2 gene (excision repair cross-complementing rodent repair deficiency, complementation group 2 [xeroderma pigmentosum D]) (previously XPD), encoding a DNA repair protein, is involved in nucleotide excision repair and basal transcription. To test the effect of the polymorphism ERCC2 Lys751Gln on the risk of lung cancer in a northeastern Chinese population, a hospital-based case-control study was designed consisting of 147 newly diagnosed and previously untreated subjects with lung cancer and 145 cancer-free control subjects matched on age (+/-3 years), gender, and ethnicity. Among the controls, the allele frequency of the C-allele of ERCC2 Lys751Gln was 0.02. The C-allele of ERCC2 Lys751Gln was significantly overrepresented among lung cancer cases (C versus A: adjusted odds ratio OR(adj) = 2.61, 95% CI = 1.12-6.05, P = 0.03). The carriers of AC genotype were at 2.78-fold (OR(adj) = 2.78, 95% CI = 1.12-6.93) higher risk of lung cancer than carriers of the AA genotype. Subdivided by tumor type, carriers of AC genotype had a 4.65-fold higher risk of squamous cell carcinoma of lung compared with carriers of AA genotype (OR(adj) = 4.65, 95% CI = 1.67-12.98, P = 0.003); similar, but not statistically significant estimates were found for adenocarcinoma of lung. In conclusion, our results suggest that ERCC2 Lys751Gln(C) allele is a potential risk marker for lung cancer in this northeastern Chinese population.