The aims of this case-control study involving 83 pairs of gastric cancer patients and sex, and age-matched healthy controls are to elucidate the relationship between the genotypes of cancer susceptibility genes (such as L-myc, CYPIA1, CYPIIE1, GSTT1, GSTM1, and AGT) and the development of gastric cancer. The results and conclusions obtained are as follows. (1) In gastric cancer, the odds ratio of smoking was 3.3 (95% CI=1.3-8.4, P=0.01); indicating that smoking was a major risk factor for gastric cancer. (2) The odds ratio of L-myc L allele was close to one, suggesting little association with gastric cancer. (3) The odds ratios for CYPIA1 Ile-Val and GSTM 1 non-null genotype were 0.5(95% CI=0.3-1.l and 0.2-1.1; P=0.08 and 0.10, respectively); therefore, they seemed to show protective effects. (4) The odds ratio of CYPIIE1 c2/c2 genotype was found to be 6.5 (95% CI=1.1-38.1, P=0.04); thus, CYPIIE1 c2 allele was a susceptible allele for gastric cancer. (5) GSTT1 non-null genotype was also a susceptible genotype for gastric cancer, because its odds ratio was 1.9 (95% CI=0.9-3.9, P=0.07).