We present the case of a 67-year-old man with adenocarcinoma of the ileal neobladder 20 years after radical cystoprostatectomy for Stage pT2 transitional bladder cell cancer. A MEDLINE research revealed 9 other cases of the development of a neoplasm in the ileal part of an ileocystoplasty. This observation supports the hypothesis that in an ileal neobladder morphologic and molecular changes can be observed similar to those in the development of colorectal carcinoma. Patients who had an ileal neobladder created are at risk of glandular malignancy and should be closely followed up.