In this cross-sectional study, we evaluated H. pylori seroprevalence and the relevant factors in 1518 people aged ≥ 6 years from the general population of Nahavand, western Islamic Republic of Iran. Questionnaires covering sociodemographic variables were completed by interview. Blood samples were taken from each individual. Sera were tested for anti-H. pylori IgG using commercial enzyme immunoassay. Overall, seroprevalence of H. pylori was high, 71.0% (95% CI 69.0%–73.0%). There was a gradual increase with age. Based on multivariate adjustment, only female sex and age could be considered risk factors.