Associations between anti-Helicobacter pylori seropositivity (HP+) and interleukin 1B (IL-1B) C-31T polymorphism have been reported and little is known about the host factors involved in the development of atrophic gastritis (AG) among infected individuals. This study aimed to examine the IL-1B C-31T polymorphism among anti-HP antibody seropositive Japanese descendants with AG in Brazil and to investigate the interactions with lifestyle factors. Subjects were 455 seropositive from four cities in Brazil, aged 33-69 years. Sex-age-adjusted odds ratio (OR) of AG for 61 current smokers was 1.29, 95% confidence interval (CI): 0.18-9.26 for T/T, while that for 325 never smokers was 0.52, 95% CI: 0.27-0.98. A negative association for AG and never alcohol drinking, every day fruit consumption and milk drinking, and less frequently coffee drinking in individuals with C/T or T/T genotype was observed. This study suggested that host genetic constitution and lifestyle factors may influence the protective effect for AG development.