Duodenogastric reflux is a pathophysiological phenomen occurring after motility disturbances on the antroduodenal junction and after operative procedures destroying, removing or bypassing the pylorus. The reflux of bile can lead to a symptomatic chronicatrophic gastritis and is an important factor in the pathogenesis of gastric ulcer type I. The pyloric regurgitation test, marking of the bile with Bromsulphalein or 14C-chenodesoxycholic acid are reliable methods to prove reflux. For treatment of bile reflux and postoperative alkaline reflux gastritis substances augmenting antral peristalsis and binding bile acids can be used. More effective are surgical procedures diverting the bile flow from the stomach or the gastric remnant.