We report a case of a large malignant neurofibroma of the urinary bladder occurring in a 33-year-old patient with Recklinghausen's neurofibromatosis. Urologic manifestations of neurofibromatosis are infrequent; a neurofibroma of the bladder with malignant degeneration is an extreme rarity. To date only 3 cases have been described in the literature.