Primary signet ring cell adenocarcinoma of the bladder accounts for less than 1 per cent of all primary bladder neoplasms. This tumor is insidious because of its subepithelial infiltrative nature, which makes diagnosis possible only late in the course of the disease. Survival is poor; greater than 50 per cent of the patients are dead within a year after diagnosis. Exenterative procedures offer the only hope of palliation; irradiation and chemotherapy have not been effective. We add 5 cases of primary signet ring cell adenocarcinoma of the bladder and 1 case of high grade transitional cell carcinoma of the bladder with signet ring cell foci to the 14 cases reported in the literature. Pathological correlation supports the origin of this neoplasm from totipotential transitional epithelium.