From 1968 to 1978, 246 patients underwent surgical exploration for renal adenocarcinoma at our clinic. Of these patients 241 had complete tumor excision and 5 had biopsy only. Correlation of the clinical and pathological data of these patients with the clinical course identified prognostic parameters. Disease progression was uncommon when the tumor was contained within the capsule of the kidney (9 of 80 patients). Perinephric tumor extension indicated a worse prognosis (11 of 40 patients with progression) that was not altered significantly by the presence of renal vein involvement (17 of 35 patients with progression). Inferior vena caval involvement or regional lymph node metastases worsened the prognosis markedly, with 8 of 11 and 8 of 9 patients demonstrating progressive disease, respectively. The worst prognosis was seen in patients with metastatic disease at operation (66 of the 71 patients dying of the disease by the end of followup). The disease was classified according to the tumor, node and metastasis system of the American Joint Committee and a stage grouping system has been suggested.