Background. Interkeukin-1 (IL-1) gene cluster polymorphisms that are thought to enhance the production of IL-1β are associated with an increased risk of gastric cancer. To determine the role of host genetic factors in Helicobacter pylori infection, we examined the relationship between gastric mucosal IL-1β levels and IL-1β polymorphisms in patients with H. pylori infection. Methods. Biopsy tissues obtained from 99 patients were homogenized and gastric mucosal IL-1β levels were measured by enzyme-linked immunosorbent assay (ELISA). Single-base polymorphisms at positions -511 and -31 in IL-1β were analyzed. Results. The IL-1β level in the antrum was significantly higher in genotype IL-1β -511C/C than in H. pylori -negative patients (P < 0.05). The IL-1β polymorphism did not influence the degree of gastric neutrophil and mononuclear cell infiltration, or gastric atrophy. IL-1β levels in the corpus, but not those in the antrum, correlated to the severity of gastric atrophy. Conclusions. These findings indicate that IL-1β polymorphisms enhance IL-1β production in the antrum; however, other factors might regulate the production of IL-1β in the corpus of the stomach, regardless of IL-1β polymorphisms, and high IL-1β production may be associated with the grade of gastric atrophy in the corpus mucosa in patients with H. pylori infection. Background. Interkeukin-1 (IL-1) gene cluster polymorphisms that are thought to enhance the production of IL-1β are associated with an increased risk of gastric cancer. To determine the role of host genetic factors in Helicobacter pylori infection, we examined the relationship between gastric mucosal IL-1β levels and IL-1β polymorphisms in patients with H. pylori infection. Methods. Biopsy tissues obtained from 99 patients were homogenized and gastric mucosal IL-1β levels were measured by enzyme-linked immunosorbent assay (ELISA). Single-base polymorphisms at positions -511 and -31 in IL-1β were analyzed. Results. The IL-1β level in the antrum was significantly higher in genotype IL-1β -511C / C than in H. pylori -negative patients (P <0.05). The IL-1β polymorphism did not affect the degree of gastric neutrophil and mononuclear cell infiltration, or gastric atrophy. IL-1β levels in the corpus, but not those in the antrum, correlated to the severity of gastric atrophy. Conclu sions. These findings indicate that IL-1β polymorphisms enhance IL-1β production in the antrum; however, other factors might regulate the production of IL-1β in the corpus of the stomach, regardless of IL-1β polymorphisms, and high IL- production may be associated with the grade of gastric atrophy in the corpus mucosa in patients with H. pylori infection.