The effects of high-energy shock waves (HESW) on the human renal cell carcinoma were examined. The kidneys were available from 32 patients treated by radical nephrectomy due to renal cell carcinoma. Immediately after nephrectomy the kidneys were perfused with cold HTK solution and stored for a maximum of 4 h in hypothermia at 8 degrees C. The tumors were treated with 4,000 shocks (65 mPa = 0.6 mJ/mm2) in an electromagnetic lithotriptor (Siemens Co., Erlangen, Germany). Microscopic and immunohistological examinations of the tumors were performed after treatment, and cell proliferation rates of treated and untreated specimens were analyzed by cell cultures in 10 cases. HESW induce severe microscopic damage in the tumor tissue as complete rupture of the vessel walls and destruction of the tubular-formed tumor masses in the focal area. Immunohistochemistry shows intact immune reactive endothelial cells by factor 8-associated antibodies until the border to histological damage. Around this region a zone of negative antibody reaction against collagen type 4 is found. In cell cultures the proliferation rates of treated specimens were significantly lower compared to untreated. The human renal cell carcinoma seems to be susceptible for treatment with shock waves. HESW induce direct damage of tumor cells and vascular damage in the tumor which may be the primary cause of tumor necrosis.