Expressions of proliferating cell nuclear antigen (PC10), p53 protein (CMI) and c-erbB-2 (NCL-1) were immunohistochemically analysed in 123 renal adenocarcinomas with known follow-up data. c-erbB-2 protein was weakly and focally expressed in 10% of the tumours, and the expression was not related to clinical or histological variables or survival. p53 protein was expressed in 33% of the tumours. Expression of p53 protein was independent of stage, grade and prognosis, while expressions of c-erbB-2 and p53 were weakly interrelated. Proliferating cell nuclear antigen was expressed in all tumours, and the fraction of PC10-positive nuclei was significantly related to grade, stage and prognosis. Multivariate analysis of clinical, histological and immunohistochemical prognostic factors indicated that the extent of the tumour, its histological differentiation and proliferation rate of the cancer cells are the most important prognostic factors. Recurrence-free survival was related to the fraction of PC10-positive nuclei, histological differentiation, sex and expression of p53 protein. Over-expression of p53 protein was related to a long recurrence-free survival. Our results show that PC10 immunolabelling can be used to determine the prognostic category in renal adenocarcinoma, whereas the expressions of p53 protein or c-erbB-2 are only weak prognostic indicators.