We report 4 patients, 1 female and 3 males aged 26-74 years, who underwent surgical treatment for renal malignant tumors with supradiaphragmatic extension into the vena cava. All of their tumor thrombi extended to the right atrium as confirmed by magnetic resonance imaging. The distinctive symptom was liver dysfunction caused by disturbance of the hepatic vein drainage in two patients. However, there was no common symptom in these 4 patients. Preoperative metastasis was found only in the female, whose metastasis was solitary in the lung and seemed to be able to be removed easily after radical nephrectomy. All of these 4 patients had radical nephrectomy and removal of the tumor thrombi with the use of cardiopulmonary bypass and temporary exsanguination. In 3 of these patients, the liver was mobilized to expose the retrohepatic vena cava by incision of the falciform, triangular and coronary ligaments. Two patients with vena caval wall invasion had vena cavectomy and an artificial vascular graft was then sutured to replace the caval wall in one of them. Preoperative liver dysfunction was gradually improved after operation and completely recovered about 1 week later. A postoperative complication, wound infection, occurred in only one patient. Pathological examination revealed renal cell carcinoma in 3 patients and nephroblastoma in the remaining one. In renal cell carcinoma, both patients without distant metastasis were alive about 15 months postoperatively. However, the one with lung metastasis died with newly appeared multiple metastases 9 months postoperatively.(ABSTRACT TRUNCATED AT 250 WORDS)