Meta-analysis has shown that successful Helicobacter pylori eradication therapy improved atrophic gastritis and intestinal metaplasia. Moreover, successful eradication therapy against atrophic gastritis has led to the suppression of the incidence of metachronous gastric cancer. Thus, the Japanese Society for Helicobacter Research concluded that all 'H. pylori-infected persons' should be considered for eradication therapy, irrespective of any background diseases. Successful eradication can prevent transmission of this bacterium, and recent publications show that curing H. pylori infection seems to reduce the risk of gastric cancer.