Gastrointestinal involvement of neurofibromatosis occurs in as many as 25 percent of cases. Neurofibroma occurs most frequently in the stomach and jejunum, but the colon may also be involved. This condition is characterized by multiple submucosal neurofibromas of the gastrointestinal tract and cafe an lait pigmentation, bony abnormalities, and neurofibromas of both central and peripheral nerves. The lesions consist of an overgrowth of neural tissue along with other mesenchymal elements. Gastrointestinal neurofibromas may cause occult bleeding, luminal obstruction, or intussusception. Malignant transformation into neurofibrosarcoma is rare. We encountered a case of neurofibromatosis diffusely involving the left colon, the sigmoid colon, and the rectum, which resulted in herniation of the mass through the anus, with intestinal obstruction. The patient also showed skin lesions of the neurofibromatosis. We report this case with a review of the literature.