Background: The study aims to evaluate the contribution of excision repair cross-complementing group 1 (ERCC1), which plays an important role in genome integrity maintenance, to lung cancer risk. Materials and Methods: ERCC1 rs11615 and rs3212986 genotypes were identified by polymerase chain reaction-restriction fragment length polymorphism analysis and their association with lung cancer risk was examined among 358 lung cancer patients and 716 controls. Results: The proportions of CC, CT and TT for the rs11615 genotype were 43.6%, 41.6% and 14.8% in the case group and 50.0%, 41.1% and 8.9% in the control group, respectively (p for trend=0.0082). Allelic analysis showed that ERCC1 rs11615 T-allele carriers have a 1.32-fold higher risk of lung cancer than wild-type C-allele carriers [95%confidence interval (CI)=1.09-1.60, p=0.0039]. In addition, a significant interaction between the rs11615 genotype and smoking status was observed. Conclusion: The T allele of ERCC1 rs11615 jointly with smoking habits may contribute to a higher lung cancer risk in Taiwan. According to the most recent report on cancer incidence and mortality by the International Agency for Research on Cancer, lung cancer has remained as the leading cause of cancer deaths all over the world (1). An estimated 2.1 million new lung cancer cases and 1.8 million cancer-related deaths occurred worldwide in 2018 (1). The rapidly increasing cases and the high death rate have urged us to look for effective marker(s) for the prediction of the risk of lung cancer, the outcome of the prognosis and the responsiveness of patient drug treatment. The initiation and development of lung cancer is related to multiple exogenous and endogenous factors including behavioral, environmental and genetic discrepancies, among which the consumption of cigarettes is the most significant factor to be associated with lung cancer risk (2). On the other hand, the fact that about 10% to 25% of lung cancer patients are non-smokers worldwide indicates that the individual genomic influences also play a critical part for personal lung cancer etiology (3). In Taiwan, the incidence and mortality of lung cancer has been ranked on the third and first place, respectively, among different types of cancer, for several years (4). Although several biomarkers for the early detection of lung cancer are being examined during recent years (5-11), the continuous search for effective clinically practical markers and the undermining mechanisms is still largely ongoing. Our genome is regularly and frequently damaged by various kinds of endogenous and exogenous mutagens and the DNA repair systems play a vital role in protecting it from irreversible mutations that can lead to carcinogenesis (12, 13). Concerning non-small cell lung cancer, genomic instability was 571 This article is freely accessible online.