Helicobacter pylori infection remains common worldwide and is significantly associated with gastric adenocarcinoma and gastric mucosa-associated lymphoid tissue (MALT)lymphoma. This article reviews recent developments in the field of H. pylori with an emphasis on mechanisms of carcinogenesis, and the bacterial, environmental and host factors that may alter risk of developing gastric cancer or gastric MALT lymphoma. The topic of eradication of H. pylori to prevent the development of malignancy and the possibility of a vaccine against H. pylori are also explored.