Abstract: Objective To investigate the role of Ki-67 in the evaluation of liver regeneration after liver transplantation in rats. Methods Seventy-two adult male SD rats were randomly divided into 1 h cold storage group (n=36) and 6 h cold storage group (n=36). Liver samples were taken at day 1, 3, 5 after operation. The liver samples of 1 h cold storage group were divided into: (A) day 1 after transplantation, (B) day 3 after transplantation, (C) day 5 after transplantation, and the liver samples of 6 h cold storage group were divided into: (D) day 1 after transplantation, (E) day 3 after transplantation, (F) day 5 after transplantation. Liver samples of each group were stained by immunohistochemistry to hove photographs under 200X microscope and positive newborn liver cells were counted by ImageJ software. Percentages of positive cells in each group were compared. Results The expression rate of positive cells in group A, group B and group C increased gradually by time (4.97%±2.34%, 9.65%±1.68%, 19.27%±2.94%), and the expression rate of positive cells in group D, E and F were also increasing. There was significant difference between group D and F (19.24%±3.08% vs 32.97%±6.05%, P＜ 0.01), group E and F (21.98%±3.14% vs 32.97%±6.05%, P＜ 0.01). The expression rates of positive cells in group D, E and group F were significantly higher than those in group A, B and C (19.24%±3.08% vs 4.97%±2.34%, 21.98%±3.14% vs 9.65%±1.68%, 32.97%±6.05% vs 19.27%±2.94%, allP＜ 0.01). Conclusion The level of Ki-67 expression can reflect the condition of hepatocytes regeneration after liver transplantation in rats.