Helicobacter pylori is the world's most common chronic bacterial infection, colonizing more than half of the population globally. Although all strains cause persistent gastric inflammation, most cases are asymptomatic; only 15% result in peptic ulcer disease and less than 2% of cases will develop gastric adenocarcinoma or the even rarer mucosa associated lymphoma (MALT). Considerable evidence implicates H. pylori in the pathogenesis of gastric malignancies -still a major burden in much of the world. Interactions between host factors, environmental factors and specific H. pylori constituents (or virulence factors) are important in determining the outcome of infection. Despite the relative ease of eradicating H. pylori with 1-2 week course of proton pump inhibitors and antibiotics in individuals, whether to actively seek occult H. pylori infection at the population level to attempt to prevent the burden of H. pylori-associated gastric malignancy remains surprisingly controversial.