Heliobacter pylori is one of the major causes of gastroduodenal disease, including gastritis, ulcers, gastric carcinoma, and mucosa-associated lymphoid tissue (MALT) lymphoma. We believe that there are three patterns of H. pylori-associated gastritis, each associated with a different outcome. Diffuse antral-predominant gastritis (DAG) has gastritis involving mainly the antrum, less intestinal metaplasia confined to the antrum, and in the United States, is associated with 90% of the duodenal ulcers. Multifocal intestinalized pangastritis (MIP) is the most severely intestinalized of the H. pylori gastritides, and is the main risk for the development of gastric adenocarcinoma. MIP is also associated with benign gastric ulcers. Nonulcer pangastritis (NUP) is also a pangastritis, but does not have an associated ulcer and has little if any, intestinal metaplasia. NUP may rarely be the precursor to diffuse gastric adenocarcinoma. MALT lymphomas have also been found to be associated with the H. pylori gastritis and may be seen with any of the three patterns. More than half of these lymphomas will regress following H. pylori eradication, although it is uncertain how long the remissions will last. Although hyperplastic polyps have traditionally been thought to be the most common gastric polyp, the frequency of fundic gland polyps has greatly increased, possibly due to the increased use of proton-pump inhibitors, and now may be the most common of the gastric polyps. Recent reports indicate that the frequency of gastroduodenal Crohn's disease may be higher than suggested by earlier literature. In addition to the characteristic granulomas, focal gastritis, isolated giant cells, or a flat lesion in the duodenum may be seen. Most benign gastric ulcers in developed countries are now due to NSAID use, which also may produce reactive gastropathy without H. pylori infection. Gastric vascular ectasia is seen in a variety of conditions, but is most often idiopathic.