Recent advances of Campylobacter pylori (C. pylori) in human gastric disease and peptic ulcer were reviewed. C. pylori is a microaerophilic, motile, gram negative spiral rod bacterium. And all strains of C. pylori has a strong urease activity. In our experience. 91% of duodenal ulcer, 88% of gastric ulcer and 43% of control have C. pylori associated gastric mucosa. Patients of peptic ulcer with C. pylori infection were high relapse than patients of peptic ulcer without C. pylori, C. pylori is now known to be the most common and important case of pathologic gastritis, and C. pylori infection have been associated with gastric ulcer, duodenal ulcer, and non-ulcer dyspepsia. Although it has been only possible to culture C. pylori for about 6 yr in Japan, there are already sufficient data available to allow us to develop the basic framework that relates C. pylori gastritis to the causation of peptic ulcer disease.