Biopsy sampling of gastric mucosa at diagnostic endoscopy provides information that cannot be obtained by other means. The most common indication for gastric biopsy is the need to know whether or not the patient is infected with Helicobacter pylori, and whether the stomach is gastritic or not. Microscopic examination of gastric biopsy specimens, in addition to H. pylori status, provides information about the grade, extent, and topography of gastritis-related and atrophy-related lesions in the stomach. This information provides further opportunities for assessing the risk and likelihood of various gastric disorders. These are: a) The predominance or restriction of the H. pylori-related gastritis in the antrum strongly correlates with an increased risk of peptic ulcer disease, and of duodenal ulcer in particular (the duodenal ulcer phenotype of gastritis). b) The presence of atrophic gastritis (loss of normal glands) in the area of the gastric body indicates a low risk of ulcer and also a reduction in the capacity of the patient to secrete acid. c) The occurrence of advanced atrophic gastritis and intestinal metaplasia multifocally in the stomach (advanced multifocal atrophic gastritis), and in the lesser curvature and angular notch in particular, are features suggestive of an increased risk of gastric neoplasias (the gastric cancer phenotype of gastritis). d) The presence of normal and healthy gastric mucosa indicates, on the other hand, an extremely low risk of both peptic ulcer disease and gastric cancer. In addition to diagnosis of H. pylori-related gastritic lesions, routine gastric biopsies may reveal findings that indicate special forms of gastritis, such as eosinophilic, lymphocytic, reactive, or granulomatous gastritis (e.g., Crohn's gastritis), or Helicobacter heilmannii gastritis. These types of gastritis can be found incidentally in a small percentage of patients who undergo diagnostic gastroscopy for abdominal complaints.