Objective To explore the survival time, pathological change and liver regeneration in different kinds of reduced-size liver transplantation in rats using steatotic grafts. Methods Macrovesicular and microvesicular steatotic rat liver models were established by feeding rats with a diet consisting of 79% standard chow, 20% lard and 1% cholesterol for different time periods. With modified two cuff vascular anastomoses and end-to-end sutures on the bile duct, reduced-size orthotopic rat liver transplantations were performed in an attempt to explore the ratio of graft weight to recipient body weight, recipient original liver weight and histological and electron-microscopic findings in comparison with whole rat liver transplantations. Results A one-week survival rates for the rats undergoing whole liver transplantation, and those in the 70% reduced-size orthotopic liver transplantation (ROLT) group, the 60%ROLT group and the 50%ROLT group (grade Ⅰ macrosteatotic grafts) were 91.67%, 75%, 75% and 25%. A 2-week survival rate was 83.33%, 75%, 58.33% and 0 respectively. And their graft recipient body weight (GRBW) values SD were 3.56%±0.36%, 2.53%±0.15%, 2.28%±0.12% and 1.83%±0.16%, respectively. In grade Ⅱ macrosteatotic grafts, the one-week survival rate for those undergoiong whole liver transplantation and those in the 70% ROLT group was 83.33% and 25%. In the microsteatosis grafts for whole liver transplantation, 70% ROLT, 60% ROLT and 50% ROLT, the one-week survival rate was 83.33%, 75%, 75% and 33.33%; and the 2-week survival rate was 75%, 66.67%, 66.67% and 0, respectively. The survival rate of the 50% ROLT group using grade Ⅰ macrosteatotic grafts or grafts mainly with microsteatosis was significantly different from that of other groups. While using macrosteatotic grafts in grade Ⅱ, the 1-week survival rate of the 70% ROLT group was very poor. Pathological findings after operation included liver regeneration and portal space with mild lymphocyte infiltration. Improvement in steatosis and dilation of the central vein and sinusoids was observed in some rats.Conclusions In the successful and long-term survival of rat reduced-size liver transplantation using grade Ⅰmacrosteatotic grafts or grafts with microsteatosis, the GRBW values should be over 2.28%±0.12%, and the value of graft-recipient liver weight should be over 60%. Steatotic livers in grade Ⅱ should not be used as grafts in ROLT. Steatosis was improved and even totally cured in some long-term survival rats.