© 2019 University of Ankara. All rights reserved.Objective: Helicobacter pylori is a bacteria which colonizes in the gastric mucosa and it is one of the major infectious diseases throughout the world. There are findings pointing out that Helicobacter pylori can cause gastric cancer and mucosa-associated lymphoid tissue (MALT) lymphoma. There are several studies on the mechanism of action of this bacterium and it is indicated that both epigenetic and genetic mechanisms are effective in this process. In this review, we will evaluate epigenetic and genetic mechanisms caused by Helicobacter pylori through gastric carcinogenesis development. Material and Method: In order to review the epigenetic and genetic mechanisms caused by Helicobacter pylori and their roles in gastric carcinogenesis development comprehensively, the health sciences databases including PUBMED were used and particularly the scientific papers on thse sbject published in the last ten years were used. Result and Discussion: The epigenetic and genetic mechanisms caused by chronic inflammation (like oxidative stress, bacterial virulance factors, intrinsic and extrinsic fators) may trigger the gastric carcinogenesis development by Helicobacter pylori as a whole. However, all of the epigenetic and genetic alterations caused by Helicobacter pylori are not yet fully understood and more in vivo ve in vitro mechanistic studies are needed.