ABSTRACT Eosinophilic enterocolitis is a rare condition representing the least frequent manifestation of eosinophilic gastrointestinal disorders. We report a 49-year-old man who presented with abdominal pain, diarrhea, and intractable vomiting for 2 weeks. Abdominal computed tomography demonstrated gastric wall thickening with mural wall thickening of the small intestine and colon. Endoscopy revealed gastric outlet obstruction because of luminal stenosis from duodenal edema. Peripheral eosinophilia, endoscopic mucosal biopsies, and exclusion of differential diagnoses confirmed eosinophilic enterocolitis. The patient was successfully treated with a 4-week prednisone taper.