The systemic inflammatory response, as evidenced by elevated circulating concentrations of C-reactive protein, is a stage-independent prognostic factor in patients undergoing curative nephrectomy for localised renal cancer. However, it is not clear whether the systemic inflammatory response arises from the tumour per se or as a result of an impaired immune cytokine response. The aim of the present study was to examine C-reactive protein, interleukin-6 and interleukin-10 concentrations before and following curative resection of renal cancer. Sixty-four patients with malignant renal disease and 12 with benign disease, undergoing resection were studied. Preoperatively, a blood sample was collected for routine laboratory analysis with a further sample stored before analysis of interleukin-6 and interleukin-10 using an enzyme-linked immunosorbent assay (ELISA) technique. The blood sampling procedure and analyses were repeated at approximately 3 months following resection. Circulating concentrations of both interleukin-6 and interleukin (P< or =0.01) were higher and a greater proportion were elevated (P<0.05) in malignant compared with benign disease. The renal cancer patients were grouped according to whether they had evidence of a systemic inflammatory response. In the inflammatory group T stage was higher (P<0.01), both interleukin-6 and interleukin-10 concentrations were higher (P<0.001) and elevated (P<0.10) compared with the non-inflammatory group. Tumour volume was weakly correlated with C-reactive protein (r(2)=0.20, P=0.002), interleukin-6 (r(2)=0.20, P=0.002) and interleukin-10 (r(2)=0.24, P=0.001). Following nephrectomy the proportion of patients with elevated C-reactive protein, interleukin-6 and interleukin-10 concentrations did not alter significantly. An elevated preoperative C-reactive protein was associated with increased tumour stage, interleukin-6 and interleukin-10 concentrations. However, resection of the primary tumour did not appear to be associated with significant normalisation of circulating concentrations of C-reactive protein, interleukin-6 or interleukin-10. Therefore, the presence of systemic inflammatory response is unlikely to be solely be determined by the tumour itself, but may be as a result of an impaired immune cytokine response in patients with renal cancer.