Immunoreactivity forp53 protein was assessed in 100 cases of primary renal-cell carcinoma (RCC). The results were correlated with clinical survival data (follow-up 24 to 84 months: mean: 39 months) and with clinico-pathological parameters, including nuclear grade, tumour stage, cell type, tumour architecture and tumour diameter. In all, 32% of the tumours were p53-positive; there was no difference in survival between p53-positive and -negative cases. Similarly, p53 expression did not correlate with any of the clinico-pathological parameters mentioned. Nuclear grade (grade 1 + 2 vs. grade 3 + 4) had a striking impact on prognosis and so, to a lesser extent, did tumour stage and the occurrence of a spindle-cell component. The immunohistochemical detection of p53 in RCC is not of prognostic value. The estimation of nuclear grade, however is a major predictor of prognosis.