AIM: To investigate the influence of IL-1B-511 gene polymorphism on IL-1B mRNA expression and gastric acid output in individual with or without Helicobacter pylori (H pylori) infection. METHODS: IL-1B mRNA expression and gastric acid secretion in 117 health volunteers were assayed using semi-quantitative RT-PCR and gastric juice assay, respectively. Pepsinogen (PG) Ⅰ and Ⅱ of 255 subjects (including 117 health volunteers) were also examined. RESULTS: T/T genotype individuals with H pylori infection had a more decreased PG Ⅰ/Ⅱ ratio. In gastric antrum mucosa, the individuals with H pylori infection had higher IL-1B expression than those without H pylori infection, but there was no obvious difference among each genotype. In gastric corpus, the individuals with H pylori infection had a significantly higher IL-1B expression than those without H pylori infection. IL-1B-511T/T genotype was markedly higher as compared with the other two genotypes. Both maximal acid output and basic acid output were similar among each genotype in IL-1B-511 gene locus, regardless of H pylori infection. CONCLUSION: IL-1B-511 T allele does not decrease gastric acid output, although it has a stimulated influence on IL-1B expression. Consequently, the pathway, through which IL-1B plays a central role in gastric cancer development, might not depend on low acid, but on the other regulation mechanisms. AIM: To investigate the influence of IL-1B-511 gene polymorphism on IL-1B mRNA expression and gastric acid output in individual with or without Helicobacter pylori (H pylori) infection. METHODS: IL-1B mRNA expression and gastric acid secretion in 117 Health volunteers were assayed using semi-quantitative RT-PCR and gastric juice assay, respectively. Pepsinogen (PG) I and II of 255 subjects including 117 health volunteers were also examined. RESULTS: T / T genotype individuals with H pylori infection had a more decreased PG Ⅰ / Ⅱ ratio. In gastric antrum mucosa, the individuals with H pylori infection had higher IL-1B expression than those without H pylori infection, but there was no obvious difference among each genotype. In gastric corpus, the individuals with H-pylori infection had a significantly higher IL-1B expression than those without H pylori infection. IL-1B-511T / T genotype was markedly higher as compared with the other two genotypes. Both maximal acid output and basic ac id output were similar among each genotype in IL-1B-511 gene locus, regardless of H pylori infection. CONCLUSION: IL-1B-511 T allele does not decrease gastric acid output, although it has a stimulated influence on IL-1B expression. The pathway, through which IL-1B plays a central role in gastric cancer development, might not depend on low acid, but on the other regulatory mechanisms.