The main role of neutrophilic granulocytes is phagocytosis and destruction of phagocytized bacteria. The nitroblue tetrazolium test (NBT), used to evaluate the bactericidal function of granulocytes, was assessed in 45 patients with renal tumour before and 14 days after renal artery embolization. No statistically significant spontaneous test NBT differences were found, compared with control group both before and 14 days after embolization. Following stimulation granulocytes in vitro by LPS of E. coli the ability of granulocytes to reduce NBT was lowered. The differences, as compared with control group, were statistically significant (p < 0.05). Our results indicates considerable impairment of lower metabolic reserve in patients with renal tumour necessary for maximum stimulation.