Bezoars are conglomerates of undigested material in the stomach. Previous reports have shown that a decrease in secretion of pepsin and gastric acid and a delay in gastric emptying might contribute to their formation. To clarify the pathogenesis of the formation of gastric bezoars, we studied gastric emptying in five patients who presented with a bezoar. In addition, gastric acid secretion was studied in three of the cases. Gastric emptying was not delayed in any case, and there was no trend toward a decrease in gastric acid secretion. The five patients were successfully treated by the endoscopic fragmentation and enzymatic dissolution of the bezoars. We conclude that, in Japanese, factors other than a delay in gastric emptying are the main contributors to bezoar formation.