Between November 2008 and March 2010, we performed initial division of the left renal vein occluded by the tumor thrombus in six cases of left renal cancer at Toranomon Hospital. The left renal vein was completely occluded by the tumor thrombus in all cases. In order to ligate the left renal artery first behind the dilated left renal vein, we must dissect the left kidney with arterial blood flow. Massive bleeding from the numerous engorged collateral veins around the left kidney is inevitable. Furthermore, access to the left renal artery is difficult because of the large tumor. We therefore initially divided the left renal vein without arterial blood flow followed by division of the left renal artery. After nephrectomy by dissecting the tumor without blood flow we extirpated the intracaval tumor thrombus. The median time of the operation was 7 hours 35 minutes and the median amount of blood loss was 2,869 ml. The tumor stage was pT3b in four cases and pT3c in two cases. No complications were observed during and after surgery except for one case of lymphocele and another case of chylous ascites. The initial division of the left renal vein is considered to be a useful surgical approach in left renal cancer with occluded left renal vein, especially when the tumor is large.