We have shown that L-myc genotype is associated with the risk of esophageal cancer from smoking and heavy drinking. In this study, we have analyzed the relationship between the L-myc genotypes and lung cancer risk from smoking in 191 Japanese lung-cancer patients and 241 non-cancer controls. The odds ratios (ORs) were markedly higher in SS and LS genotypes than in LL genotype; age-sex-adjusted ORs were 3.19, 2.30 and 0.92, respectively. This result suggests that the L-myc polymorphism may affect the induction of lung cancer by smoking. The OR for smoking in SS-genotype patients diagnosed within 2 years was higher than that in other SS patients, suggesting that smoking-related lung cancer in SS genotype might exhibit a poorer prognosis.