The content of urinary bladder cancer antigen (UBC), tissue polypeptide specific antigen (TPS), nuclear matrix protein 22 (NMP22), and the expression of LewisY carbohydrate antigens and of epidermal growth factor receptor (EGF-R) in bladder tumor tissues were determined. These included 14 well, 6 moderately and 11 poorly differentiated bladder cancers. Cytosol UBC and TPS were higher in the well and in the moderately differentiated bladder tumors than in the poorly differentiated bladder cancers; whereas cytosol NMP22 was higher in the poorly differentiated bladder cancers than in the well and in the moderately differentiated bladder tumors. The Lewis related carbohydrate antigens, evaluated by the reactivity of the tissues to monoclonal antibody B3, were highly expressed in poorly differentiated tumors. The EGF-R was strongly expressed in a large number of poorly differentiated bladder tumors. These data suggest that the determination of cytosol NMP22 and the immunoblotting with B3 and EGF-R antibodies might be useful to obtain more information on the differentiation of bladder tumors.