Tumor resection and caval tumor thrombectomy, with or without cavotomy and inferior vena cava (IVC) replacement are sometimes performed in patients with renal cell carcinoma (RCC) extending into the IVC or liver tumors invading the IVC. Two such cases were treated. Case 1: a 68-year-old female was transferred with a diagnosis of right RCC with tumor thrombus extending into the IVC. A plication was performed to prevent extension into the right atrium before the nephrectomy and cavotomy with removal of the tumor thrombus was accomplished, because the IVC was almost completely obstructed and the hemodynamics were stable during cross-clamping of the IVC. Case 2: a 37-year-old female was transferred with a diagnosis of a giant metastatic liver tumor. A trisegmentectomy with resection of the invaded IVC and IVC replacement was performed while the abdominal aorta was cross-clamped to maintain the hemodynamics. Therefore, abdominal aortic cross-clamping was convenient to maintain the hemodynamics when the IVC replacement was performed during IVC cross-clamping.