Expression of p53 and MiB1, markers of tumor proliferation, was evaluated in human bladder tumors, and correlated with ploidy and cancer progression in 83 consecutive patients. Transurethral resection of a newly diagnosed bladder tumor was performed in 73 cases, and systematic bladder biopsies were performed in 10 cases after bacillus Calmette-Guerin (BCG) treatment. p53 and MiB1 expression were performed by an immunohistochemical technique and the ploidy was determined on a frozen fragment of the tumor. p53 expression was correlated in relation to grade, stage and combination of grade and stage. MiB1 expression was correlated with cytological grade, and a significant difference was demonstrated between pT0 and pTa, pTa, and pT1, pTa and pT2 tumors but not between pT1 and > or = pT2 tumors. A discordance was observed for the comparison of p53 and MiB1 values, stage by stage, suggesting that these two techniques are independent of each other. A larger proportion of aneuploid tumors were positive for p53 and MiB1 (64.8 vs. 86.5%, respectively), but p53 and MiB1 immunostaining were not better indicators than ploidy alone to predict cancer progression.