A 20-year-old woman is presented who had eosinophilic gastroenteritis of the muscularis and serosal type which involved the terminal ileum. The diagnosis was initially acute appendicitis, but clues to the correct diagnosis included the presence of malabsorption, protein-losing enteropathy, abdominal pain and ascites, and especially a history of recurrent bouts. Peripheral eosinophilia is found in most cases and biopsy, or a peritoneal tap when ascites is present, may demonstrate a predominantly eosinophilic infiltration. Radiographic findings include a rigid, open ileocecal valve. There is rapid response to corticosteroid therapy, but long term follow-up is required because the disease may run a chronic, relapsing course.