Fifty-three (22 p. 100) of 247 cases of renal parenchyma cancer seen between 1963 and 1978 were Robson's stage III cancers. Of the 211 patients treated by enlarged nephrectomy 18 (8.5 p. 100) had lymph node invasion, 35 venous extension without lymph node involvement, and 8 simultaneous spread into the large renal vessels or inferior vena cava and lymph nodes. Of the 10 patients N+ V0 operated upon, one died postoperatively and 7 from cancer, including 6 with a less than 5-year survival. There are only two survivors. Only one of the 8 patients with both lymph node and vein involvement operated upon is still alive. Ten (58.8 p. 100) of the 17 patients undergoing surgery with renal vein extension but no invasion of the inferior vena cava or lymph nodes, and truly exposed to a 5-year postoperative follow-up period, lived for 5 years and 9 of these are still alive. Invasion of the inferior vena cava in the absence of lymph node involvement (11 cases operated) produced no recurrence of the tumor in 5 patients after a prolonged follow-up period. These findings, together with those published in the literature, suggest the need for modifying Robson's classification.