Currently no ideal preventive modalities are available for reducing gastric-cancer caused mortality in organized population-based application. The primary objective of the study is to determine if H.pylori screening followed by eradication of positive subjects and endoscopic follow-up of those with serological evidence of atrophic gastritis reduces mortality from gastric cancer in middle-aged people in high-risk areas. The GISTAR study is a multicenter randomized study of H.pylori eradication and pepsinogen testing for prevention of gastric cancer mortality. Altogether 30.000 individuals aged 40-64 years will be enrolled, providing 90% study power to detect at least 35% reduction in gastric cancer mortality at 15 years of follow-up. Participants will be randomly allocated to one of two groups. In the active investigation/management group those positive for H.pylori will be offered eradication therapy and individuals with decreased pepsinogen I/II ratio will be invited for endoscopy. The control group will receive standard health care. The primary endpoint for this trial will be the mortality difference from gastric cancer between the two groups at 15 years or when enough cases accumulate to demonstrate a statistical difference. The study is expected to provide valuable information on the utility for reduction in gastric cancer mortality of: 1) H.pylori eradication in adults on a population-basis, including subjects who may already have pre-malignant lesions; and 2) pepsinogen testing in screening settings. A pilot study of 3,455 individuals prior to the main trial was conducted from October 2013 to December 2016.