Helicobacter pylori is one of the most common bacteria responsible for chronic infection worldwide. Its reservoir is essentially human. The transmission of H. pylori seems to be direct from person-to-person, however, a common source cannot be totally excluded. Two routes of transmission have been proposed: faecal-oral and oral-oral, based on the following arguments: H. pylori has been cultured from faeces and seems to survive in water in non-culturable forms. Although certain epidemiological studies have suggested waterborne and foodborne transmission, there has been no confirmation of this. H. pylori has been cultured from the oral cavity in several studies and there is some indirect but scarce evidence for oral-oral transmission. Further study of its molecular epidemiology should provide greater insights into this as yet unsolved question.