The predictive strengths of the third and new fourth editions of the tumor, nodes and metastasis classification are compared using 872 cases of operatively treated renal cell carcinoma. The new tumor, nodes and metastasis classification facilitates an improved assessment of prognosis by subdivision of the former category pT3 into pT3a and pT3b. The new pN classification permits recognition of an especially unfavorable subgroup (pN3) in patients with regional lymph node metastases. The new stage grouping makes a rough subdivision of patients into groups with different prognoses. However, stages 1 and 2 show similar survival rates. Compared to the commonly used Robson stages, the International Union Against Cancer stage grouping has advantages as well as disadvantages. Any resulting recommendations for modification of stages should be subject to testing by other institutions.