Abstract: Helicobacter pylori (Hp) has been confirmed as the most important risk factor for non-cardia gastric ade-nocarcinomas and gastric mucosa-associated lymphoid tissue (MALT) lymphomas. Eradication therapy hasproven beneficial when given prior to the development of intestinal metaplasia. However, Hp eradication alonewill have only a moderate effect on gastric cancer incidence worldwide. The mechanisms between Hp andgastric malignancies have not yet been fully illuminated. The pro-carcinogenic effects of Hp could be relatedto the complex and evolving pathways of altering signal transduction pathways within gastric epithelial cellsthat are stimulated by adherence and translocation of Hp products through its type IV secretory system. Inthis article, we review the role of Hp infection in the occurrence and development of gastric cancer.