The allergic bowel diseases of the adolescent have been traditionally lumped under the diagnosis of allergic or eosinophilic gastroenteritis. Over the past 20 years, clinical criteria have been established to distinguish three distinct clinical syndromes: eosinophilic esophagitis, eosinophilic gastroenteritis, and eosinophilic ascites. Each has a characteristic infiltration of eosinophils in, respectively,the esophagus only, the stomach, small bowel, and/or large bowel, or the serosal surface of the bowel. These conditions are distinguished by clinical presentation, diagnostic features, and treatment alternatives. Teenagers with these conditions may present to their pediatrician, family physician, allergist, or gastroenterologist, so each physician must appreciate the extent of appropriate diagnostic investigations and the relative value of dietary or anti-inflammatory therapy.