In a prospective study of 511 patients we compared the data of 320 who underwent systematically extended dissection of the regional lymph nodes with data of 191 who underwent only facultative dissection of the lymph nodes, which means that no lymph nodes had been removed or only a few were taken for staging purposes. Only patients without distant metastases and who were less than 72 years old were included. All patients were treated with a transabdominal approach. The incidence of positive nodes in the patients with systematically extended lymphadenectomy was 17.5% and for patients with facultative lymphadenectomy it was 10%. Survival rates of patients with facultative lymphadenectomy were 58% after 5 years and 40.9% after 10 years, compared to 66% and 56.1%, respectively, for patients with systematically extended lymphadenectomy (p less than 0.01). Patients with stage pT1-2 (Robson stage I) and pT3aN0M0 (Robson stage II) tumor obviously had the highest benefits with extended lymphadenectomy. Operative mortality was less than 1% after systematically extended lymphadenectomy and 3.8% after facultative lymphadenectomy. We conclude from our data that the systematic and extended lymphadenectomy improves the prognosis of patients with renal cell carcinoma without any additional operative risks.