Objectives: This study was performed to investigate sweets of genetic polymorphisms of glutathione S-transferase M1 (GSTM1), glutathione S-transferase M1 (GSTT1), cytochrome P450 1A1 (CYP1A1) and cytoehrome P450 2E1 (CYP2E1) on lung cancer development. Methods: Ninety-eight lung cancer patients and 98 age-sex matched non-cancer patients hospitalized in Chungbuk National University Hospital form March 1997 to August 1998, were the subjects of this case-control study. Direct interview was done and genotypes of GSTM1, GSTT1, CYP1A1 and CYP2E1 were investigated using multiplex PCR or PCR-RFLP methods with DNA extracted from venous blood. Effects of the polymorphisms of GSTM1, GSTT1, CYP1A1 and CYP2E1, lifestyle factors including smoking, and their interactions on lung rancor were statistically analyzed. Results: GSTM1 was deleted in 67.01% of the cases and 58.16% of the controls, and the odds ratio(95% CI) was 1.46(0.82-2.62). GSTT1 deletion was 58.76% for the lung cancer patients and 50.00% for the controls[OR:1.43(0.81-2.51)]. The frequencies of lle/lle, lle/Val and Val/Val of the CYP1A1 polymorphisms were 59.18-18%, 35.71%, and 5.10% for the cases, and 52.04%, 45.92%, 2.04% for the controls, respectively. Risk of lung cancer was not associated with polymorphism of CYP1A1 ($x^2trend=0.253$, p-value>0.05). The respective frequency of c1/c1 c1/c2, c2/c2 genotypes for CYP2E1 were 50.00%, 42.86%, 7.14% for the lung cancer patients, and 66.33%, 30.61%, 3.06% for the controls $(x^2trend=5.783,\;p<0.05)$. c2 allele was a significant risk factor for lung cancer. We also observed a significant association of cigarette smoking history with lung cancer risk. The odds ratio(95% Cl) of cigarette smoking was 3.03(1.58-5.81). In multiple logistic analysis including genotypes of GSTM1, GSTT1, CYP1A1 and CYP2E1, and smoking habit, only snaking habit came out to be a significant risk factor for lung cancer. Conclusion: Genetic polymorphisms of GSTM1, GSTT1, CYP1A1 and CYP2E1 are not so strongly associated with lung cancer as lifestyle factors including cigarette smoking.