Abstract Helicobacter pylori are gram-negative bacteria that colonize the gastric epithelia of approximately 50% of the world’s population. This infection is considered to be the leading known cause of chronic gastritis, peptic gastric diseases. The association of extra-gastric diseases with colon cancer and other colonic neoplasms has EHHQWKHVXEMHFWRIPXFKGHEDWHVLQFHLWZDV?UVWVXJJHVWHG$OWKRXJKVRPHVWXGLHVKDYHFDVWGRXEWRQWKLVassociation, others have sustained it. These include a recent meta-analysis and cross-sectional study of more than 150,000 patients which is the largest on this subject so far. In addition, there are numerous articles that support the biological plausibility of this association. In this article we review the available evidence regarding this association and the mechanisms of causality that have been proposed. Keywords +HOLFREDFWHUS\ORULSRO\SVFDQFHULQADPPDWLRQ INTRODUCTION Helicobacter pylori (H. pylori) is a spiral gram-negative bacillus that infects human gastric epithelia (1). It was first cultivated by Warren and Marshall in 1983 (2). It infects approximately 50% of the world’s population (3, 4), although its prevalence varies significantly among geo-graphical areas, social classes, ages and races (5-7). Fifteen years ago this bacteria was classified as a Type 1 human car -cinogen, by the World Health Organization’s International Agency for Research on Cancer (IARC) (8). H. pylori, hepatitis B, hepatitis C and human papillomavirus are the four infectious agents that cause more than 90% of cancers associated with infections (9). These bacteria have causal relationships with a series of gastric diseases including chronic gastritis, gastric cancer, peptic ulcers and MALT lymphoma (10-12). However, the percentage of infected people who develop clinically significant disease is low (20%) and development of clinically significant disease requires coexistence with the bacteria for decades, indi-vidual genetic susceptibility and depends on bacterial viru -lence factors (13, 14). In addition to the gastric diseases mentioned, it has been suggested that H. pylori can also be associated with extraintestinal entities such as coronary disease, neurodegenerative diseases and hematological diseases. Certainty is greatest for hematological diseases (14-23). Although published data are contradictory polyps and adenocarcinoma of the colon have recently been associ-ated with H. pylori infections (24-27). This review aims to bring together and discuss the currently available evidence concerning the relationship between H. pylori and colon cancer and the mechanisms proposed for this association.