A number of reports on the pathogenic influence of Campylobacter concisus on the human body and its role in many diseases of the gastrointestinal system, including gastroesophageal reflux disease, Barrett's esophagus and inflammatory bowel disease, have appeared lately. Campylobacter concisus is a Gram negative bacteria which requires an anaerobic environment or microaerophilic environment with hydrogen for growth and is therefore difficult to culture. Due to this difficulty, the rate of infections in epidemiological data are underestimated. There are reports that C. concisus was the only pathogen isolated from the stool of patients with acute diarrhea, which could indicate that it is an etiologic factor of acute gastrointestinal infections in humans. Moreover, the results of some studies suggest that infection with C. concisus is a factor predisposing to the development of gastroesophageal reflux disease and Barrett's esophagus, conditions which may be present before the development of cancer. There are also studies which indicate C. concisus infection as a trigger of inflammatory bowel disease, since it has been demonstrated that C. concisus is present more frequently in patients with newly diagnosed Crohn's disease than in a control group.