Renal cell carcinoma extends into the lumen of the inferior vena cava in approximately 4% of patients at the time of diagnosis. Surgical removal of the intracaval tumor thrombus with radical nephrectomy is the preferred treatment for this malignancy. From January 1977 to June 1990, 31 such patients were examined for combined problems of renal carcinoma and intracaval tumor extension. Twenty-six of these patients underwent radical nephrectomy and vena caval thrombectomy. Ten patients had tumor thrombus confined to the infrahepatic vena cava, 11 had retrohepatic caval involvement, and 5 had extension to the level of the diaphragm or into the right atrium. Surgical approach was dictated by the level of caval involvement. Control of the suprahepatic vena cava plus temporary occlusion of hepatic arterial and portal venous inflow were necessary in some cases; cardiopulmonary bypass was required for transatrial removal of more extensive tumors. Five of the 26 patients had evidence before operation of distant metastatic disease; none of these survived beyond 12 months. The 5-year actuarial survival rate of the 21 patients without known preoperative metastatic disease was 57%. Complete surgical excision of all gross tumor appears to be critical for long-term survival in these patients.