The expression of p53, c-erbB-2, bcl-2 and c-myc proteins was compared to the quantity of the nucleolar organiser regions (AgNORs) and MIB-1 antigen to elucidate the relationship between oncogene expression and rapidity of cell proliferation and tumor growth fraction. Sections from 50 male breast carcinomas (MBC) and 62 superficial papillary bladder neoplasias were stained with the standardised AgNOR method and monoclonal antibodies MIB-1, DO7, CB11, bcl-2 124 and 9E11. p53 immunopositivity was associated with high AgNOR quantity and MIB-1 scores both in MBC and bladder neoplasm. c-erbB-2 expression was associated with high AgNOR quantity in bladder neoplasm. bcl-2 expression was associated with low AgNOR quantity in MBC. c-myc expression was associated with high AgNOR quantity in MBC. MBC patients with low AgNOR quantity, and p53, c-erbB-2 and c-myc immunonegativity had the longest overall survival. Patients with bladder neoplasia with low AgNOR quantity, negative p53 and positive c-erbB-2 immunostaining had the longest disease-free survival time. Our results indicate that p53 overexpression reflects both the rapidity of cell proliferation, as assessed by AgNOR quantity, and tumor growth fraction, as assessed by MIB-1 scores, while c-erbB-2, c-myc and bcl-2 expression mainly reflects the rapidity of cell proliferation. The combination of AgNOR quantity and oncogene expression may stratify patients into different risk groups.