Gastrointestinal ganglioneuromatosis is a rare neoplastic condition that can occur in association with von Recklinghausen's disease with multiple endocrine neoplasia type II B. The main locations are the ileum, colon, and appendix. We report a case of diffuse ganglioneuromatosis of the appendix associated with a mesenteric and ileocecal plexiform neurofibroma in von Recklinghausen's disease.