Objective To investigate the changes of liver regeneration capacity after partial hepatectomy in ob/ ob mice with leptin gene defect and the effects of genipin on their liver regeneration. Methods Twenty ob/ ob mice were randomly divided into two groups: genipin (obG) and PBS groups (obP). They were randomly divided into 2? and 10?d groups according to the time elapsed after hepatectomy. C57BL/6J mice served as a control group. Serum and liver samples were collected from the mice. The rate of liver regeneration was calculated, the rate of positivity for proliferating cell nuclear antigen (PCNA) was determined by immunohistochemical staining, and the DNA content of hepatocytes was determined by Feulgen staining. Moreover, the expression of signal transducer and activator of transcription 3 (STAT3) was determined by Western blotting and liver function indicators were tested by serum biochemical method. Results Compared with those in C57BL/6J mice, the liver cells were filled with lipid droplets of varying sizes, and exhibited ballooning degeneration and focal necrosis in ob/ ob mice; the liver regeneration rate ( P < 0. 05), number of PCNA?positive cells ( P < 0. 01), and hepatocyte DNA content ( P < 0. 01) decreased significantly in the latter mice. Compared with the levels in the solvent group, the degree of hepatocytic lesions was reduced and the number of binucleated hepatocytes was significantly increased in the genipin group. In addition, the liver regeneration rate ( P < 0. 05), number of PCNA?positive cells ( P < 0. 01), and DNA content of hepatocytes ( P < 0. 01) in the genipin group were higher than those in the PBS group. The levels of ALT, AST, and LDH in the genipin group were lower than in the PBS group ( P <0. 05), while the expression of p?STAT3 in the genipin group was increased ( P < 0. 05). Conclusions Fatty liver ob/ob mice exhibit delayed liver regeneration after partial hepatectomy. Genipin promotes liver regeneration and improves liver function in ob/ ob mice.