To analyze the cause of abdominal hemorrhage after reduce-size liver transplantation in rats. Healthy female SD rats were used as the donors and male SD rats as the recipients (weighing 260-280 g), with the recipients weighing 10 g more than that of the donors. The donor operation was performed by the same surgeon under direct vision, and the liver graft size reduction procedure was completed in the donor operation. The recipient operation was performed by two surgeons under direct vision. A total of 270 SD rats received reduce-size liver transplantation successfully, and 44 of the rats died from intra-abdominal hemorrhage. The abdominal hemorrhages, listed in the order of incidences, included anastomotic hemorrhage of the inferior vena cava of the superior liver (28 cases), subcapsular hemorrhage of the liver (9 cases), ligation hemorrhage of the left outboard lobe, the nipple lobe and the triangle lobe of the liver (9 , 7 and 7 cases, respectively), hemorrhage of the right suprarenal vein and lumbar veins (5 cases), hemorrhage of the mechanical injury (4 cases), cuff hemorrhage of the portal vein and inferior vein cava of the inferior liver (both 4 cases). Eight rats had anastomotic hemorrhage of the inferior vena cava of the superior liver and ligation hemorrhage of the left outboard lobe, 5 had hemorrhage of the two ligation points of the reduce-size liver; for management of the hemorrhage, 10 rats received suture or/and ligature, and 6 had washing and hot water bath. The most common cause of hemorrhage after reduce-size liver transplantation in rats is the anastomotic hemorrhage of the inferior vena cava of the superior liver, and this finding may provide clues for improving the success rate of reduced size liver transplantation in rats.