The presence of spiral-shaped micro-organisms in the human stomach was described over 100 years ago by Polish clinical researcher, Professor W. Jaworski at Cracow Jagiellonian University. Their presence was then confirmed in animals by G. Bizzazero, but was not really taken seriously until the late 1970s, when J.R. Warren, a pathologist in Perth, Australia, noted the appearance of spiral bacteria overlaying gastric mucosa, chiefly over inflamed tissue. Warren and B.J. Marshall cultured these organisms in 1982 from 11 patients with gastritis and were able to demonstrate a strong association between the presence of Helicobacter pylori (H. pylori) and the finding of inflammation in gastric biopsies. People, who did not exhibit gastritis, also did not have the organism, a finding which was confirmed in a number of studies. Originally called Campylobacter pyloridis, the name was changed to Campylobacter pylori, and then later to Helicobacter pylori (H. pylori) as specific morphologic, structural, and genetic features indicated that it should be placed in a new genus. Marshall elegantly fulfilled Koch's postulates for the role of H. pylori in antral gastritis with the self administration of H. pylori, and also showed that it could be cured by use of antibiotics and bismuth salts. Most persons who are infected with H. pylori never suffer any symptoms related to the infection; however, H. pylori causes chronic active, chronic persistent, and atrophic gastritis in adults and children. Infection with H. pylori also causes duodenal and gastric ulcers. Infected persons have a 2- to 6-fold increased risk of developing gastric cancer and mucosal-associated-lymphoid-type (MALT) lymphoma compared with their uninfected counterparts. The role of H. pylori in non-ulcer dyspepsia remains unclear. These practical aspects of H. pylori were subjects of two international symposia organized by us in 1995 and 1997 in Cracow, helping to promote research and Polish consensus regarding treatment of H. pylori infection.