Combined resection of the inferior vena cava for hepatobiliary malignancies remains a technical challenge. We successfully resected an intrahepatic cholangiocarcinoma involving the retrohepatic vena cava, and reconstructed the caval defect using a left renal vein patch graft. The patient was a 79-year-old man. Preoperative ultrasonography and computed tomography revealed that the tumor was located in the right lobe of the liver and was about 6 cm in diameter. Arteriogram revealed encasement of the right arterial and portal branches. Magnetic resonance imaging scan revealed that the tumor involved the retrohepatic vena cava. The patient underwent a right hepatectomy combined with resection of the retrohepatic vena cava. The resected portion of the caval wall was 3.6 cm long and 2.7 cm wide. The caval defect was reconstructed using a left renal vein patch graft of a rhomboid shape, which was made by oblique incision of the vein graft. The postoperative course was uneventful. Postoperative cavogram showed adequate patency of the reconstructed retrohepatic vena cava. The patient was disease-free 22 months after surgery. In conclusion, major liver resection combined with caval resection and reconstruction can be performed safely. Furthermore, a left renal vein graft can provide a flexible patch according to the form and size of the caval defect.