| Gastric cancer is the most common malignancy of the gastrointestinal tract cancer and also the leading cause of gastrointestinal cancer-related death worldwide. A clear association between Helicobacter pylori infection and gastric cancer was established years ago. Recent studies have shown that the association between H. pylori and gastric cancer has probably been underestimated. This may have resulted from negative H. pylori status in subjects after loss of colonization in the presence of atrophic gastritis and intestinal metaplasia, prior to development of gastric cancer. The recognition of the central role of H. pylori in carcinogenesis has increased expectations of gastric cancer prevention by H. pylori eradication. A primary preventive effect of eradication in subjects with H. pylori-induced gastritis has been demonstrated. However, a secondary preventive effect in patients with pre-malignant gastric lesions is still controversial, especially in patients with intestinal metaplasia and dysplasia. H. pylori eradication thus has the largest preventive impact if given at the earliest stage of gastric carcinogenesis. This treatment policy requires confirmation; results of ongoing randomized controlled trials are therefore eagerly awaited. During the presentation, we will discuss the strength of the association between H. pylori and gastric cancer, host and microbial factors that influence this correlation, and interventions that can lead to a decline in gastric cancer incidence in high and low incidence countries.