Eosinophilic inflammation may occur in any part of the intestinal tract from the esophagus to the rectum. Despite 70 yr having passed since the first reference to a case of eosinophilic gastroenteritis, the epidemiology and natural history of eosinophilic gastrointestinal disorders are still poorly known. Insights into their etiology and pathogenesis have revealed an important role for allergens; interleukins 4, 5, and 13; the eotaxin family of chemokines; and eosinophil-derived proteins. Diagnosis is confirmed by typical histologic features in a patient with a suggestive clinical phenotype. Treatment involves eliminating triggering allergens, making dietary restrictions the first choice of therapy in a compliant patient; corticosteroids [topical in eosinophilic esophagitis (EE)], despite the potential for serious side effects, are used with success in refractory and non-compliant patients. In this study we discuss EE and gastroduodenitis against the backdrop of clinical case presentations.