Eosinophilic gastroenteritis, an inflammatory disease of unknown etiology, commonly involves the stomach and small intestine with eosinophilic infiltration. Herein we describe an unusual case of eosinophilic gastroenteritis involving the entire digestive tract. A 24-yr-old woman came to our hospital presenting with diarrhea with marked peripheral eosinophilia. Stool specimens were negative for parasites, ova, bacteria, and fungi. Barium and endoscopic studies showed thickened edematous folds of the duodenum and small intestine. Biopsy specimens of the esophagus, stomach, duodenum, ileum, and colon showed eosinophilic infiltration. A diagnosis of eosinophilic gastroenteritis involving the entire digestive tract was made, and therapy with prednisone was started. Symptoms and peripheral eosinophilia rapidly resolved, and biopsies of the digestive tract demonstrated no eosinophilic infiltration. This case illustrates the expanded spectrum of the disease to the entire digestive tract and emphasizes the diagnostic usefulness of endoscopic biopsies. The initial presentation of patients with eosinophilia requires the evaluation of the entire digestive tract. It is worth noting that eosinophilic gastroenteritis can involve the entire digestive tract.