We analyzed the distribution of glutathione-S-transferase P1 gene (GSTP1) polymorphism in a population from northern China and the relationship between the polymorphic BsmAI site in its exon 5 and gastric cancer susceptibility and evaluated the combined effect of GSTP1 polymorphism and H. pylori infection on gastric cancer. Blood samples were taken from 1,612 subjects in areas of high and low incidence of gastric cancer. Polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP) were performed to analyze the genotype of a GSTP1 polymorphism in exon 5 (Ile105Val). Serum levels of anti-H. pylori IgG were measured by enzymed-linked immunosorbent assay. We found that the GSTP1 Val variant allele frequency was 22%, which was significantly different from the Western people. There was a significant difference in GSTP1 allele gene distribution between the area of high incidence of gastric cancer(23%) and low incidence(20%). The frequency of GSTP1 Val/Val genotype was statistically higher in the gastric cancer group compared to the non-gastric cancer population. Analysis showed a statistically significant 1.587-fold increase in gastric cancer risk associated with the GSTP1 Val allele. Moreover, there was a statistically significant interaction (odds ratio, 17.571; 95% confidence interval, 6.207 - 49.742) between GSTP1 Val/Val genotype and positive H. pylori IgG status. Our results indicate that the distribution of GSTP1 polymorphism has geographic differences. Individuals with the GSTP1 Val allele gene show an increased risk for gastric cancer. Association of the GSTP1 (Val/Val) genotype with H. pylori IgG positive status could significantly increase gastric cancer risk.