In this study, we analyzed causes of abdominal hemorrhage after reduced-size liver transplantation in rat. Healthy SD rats (weight range of 260-280 g) underwent liver transplantation, the donors were female and the recipients were male rats. The recipients were, on average, by < 10 g heavier than the donors. All operations on donor rats were performed by the same person using unaided eyesight. Operations on recipient rats were performed by two persons using unaided eyesight. About 270 rats received reduced-size liver transplantation of which 44 died because of intra-abdominal hemorrhages. The distribution of abdominal hemorrhage sites was as follows: 28 cases with anastomotic hemorrhages of the inferior vena cava of the superior liver, 9 cases with subcapsular hemorrhage, 9 cases with tied hemorrhages from the left lateral lobe, 7 cases with hemorrhages from the papillary lobe, 7 hemorrhages from the triangular lobe, 5 hemorrhages of the right suprarenal vein and lumbar veins, 4 hemorrhages caused by mechanical injury, 4 cuff hemorrhages of the portal vein and the inferior vein cava of the inferior liver, 8 anastomotic hemorrhages of the inferior vena cava of the superior liver and the tied hemorrhage of the left outboard lobe, and 5 hemorrhages of the two tied points of the reduced-size liver. Ten hemorrhages were stopped by suture or/and ligature, and 6 were stopped by washing with or soaking in hot water. Results of this study will be helpful to raise success rates of reduced-size liver transplantation.