Carbohydrate Antigen 19-9 (CA 19-9) histological expression in transitional cell bladder carcinoma (TCBC) was studied by means of immunohistochemistry and its findings compared with those of Tissue Polypeptidic Antigen (TPA) and Carcino Embryonic Antigen (CEA). Twenty-one TCBC of various grade and stage were analyzed by using Avidin-Biotin complex method for CA 19-9 and TPA Peroxidase-Antiperoxidase method for CEA. Grade 3 and pT1, pT2/pT3 carcinomas showed a constant staining for CA 19-9 antigen, grade 2 showed a 50% positive immunoreaction while all grade 1 cases were negative. TPA showed an inverse correlation with well differentiated carcinomas which were better and more extensively stained than anaplastic ones. CEA expression was not correlated either with grade or stage. CA 19-9 could be considered as a dedifferentiation marker in TCBC.