Bezoars, accumulations of foreign material in the stomach, have been known to occur in animals and man for centuries. The incidence of bezoars in human patients has increased as a result of operative manipulation of the gastrointestinal tract. Composed of vegetable matter, hair, or more unusual materials like shellac or cement, they may lead to anorexia, weight loss, bleeding, obstruction, or perforation of the alimentary tract. Although this entity is often recognized radiologically, endoscopy provides the most accurate means for identification and classification. Many bezoars can be removed endoscopically, but some will require operative intervention. Once removed, emphasis must be placed upon prevention of recurrence. Physicians must learn to recognize and classify bezoars correctly in order to provide the most appropriate therapy in each instance.