During an 11-year period a total of 314 patients underwent surgery for renal carcinoma; 70 had venous extension of the tumour, 31 had extension to the main renal vein and were staged V1 and 39 had involvement of the inferior vena cava and were staged V2. Special attention was paid to the latter group, which was divided into 2 subgroups: V2a for caval extension without ingrowth and V2b for caval extension with infiltration of the caval wall. Thirty-eight patients with caval involvement underwent surgery, with a 13% post-operative mortality rate. Most of the patients with malignant caval ingrowth (V2b) had concomitant lymph node and distant metastases. However, some had negative lymph nodes and no metastases at the time of operation. Perifascial nephrectomy associated with caval tumour removal or lateral subhepatic caval resection for patients staged V2aNOMO significantly increased the survival rate when compared with that of patients with no surgery on the obstructed vena cava. Total resection of the completely obstructed subhepatic vena cava for patients staged V2bNOMO has limited indications but, in selected cases, may prolong survival. This retrospective study supports the reintroduction of indicator V in the TNM staging of renal carcinoma and suggests the splitting of stage V2 into V2a for patients with free-floating caval extension and V2b for caval thrombus with ingrowth and caval wall infiltration.