Objective: This study was designed to investigate how long-term highfat diet (HF) affects the body weight gain and saccharin preference in adult female rats.Methods: Adult female SD rats were randomly divided into two groups fed with HF and chow respectively for 9 weeks.Rats from each group were used in 48-hour twobottle choice (saccharin vs.water) test.The preference ratio of saccharin solution was calculated at concentrations of 0.001, 0.002, 0.005, 0.01, 0.02 and 0.04 M.Results: The HF rats gained more body weight at 5-9 weeks compared with chow group.There was no significant difference in total energy intake between the two groups.The preference ratio for 0.001 M and 0.02 M saccharin was significantly lower in the HF group than in the chow group.Conclusion: Our results suggest that long-term HF increases the body weight gain by the change of nutrition composition without increase in energy intake in female rats, and alters saccharin preference at low and high concentrations.