Eosinophilic gastroenteritis, an idiopathic inflammation of the alimentary canal, is characterized by infiltration of the intestinal wall by eosinophils, massive submucosal edema, and peripheral eosinophilia. It is generally confined to the gastric antrum and proximal small intestine. A young woman had an eosinophilic infiltrate that involved the distal ileum and right colon only. Barium studies showed severe narrowing and shortening of the cecum and ascending colon. Symptoms of intestinal obstruction did not respond satisfactorily to conservative measures. Adhesions over the ileocecal area as well as thickening and induration of the terminal ileum and proximal right colon were found on hemicolectomy. The remaining intestine and the peritoneal cavity were felt to be normal. Histologic examination showed a cellular infiltrate with prominent eosinophils in the mucosa, submucosal edema and fibrosis. During a 40-month follow-up period after the hemicolectomy, the patient has not shown clear evidence of recurrence or extension of the disease to the stomach or proximal small intestine. It is concluded that idiopathic eosinophilic gastroenteritis may primarily involve the ileocecal area. In that location it must be specifically differentiated from intestinal tuberculosis, amebiasis, and Crohn's disease.