Objective: To investigate the antidepressant effects of daidzein and its possible mechanism. Method: Kunming mice were randomly divided into the normal group

the model group

the Fluoxetine group(3.0 mg·kg-1) and the daidzein groups

10 mice in each group. Low

middle and high dose of daidzein (10

20

40 mg·kg-1)were administered. The depression model was established by chronic unpre dictable mild stress(CUMS)

the body weight and times of grooming in the open field test were detected respectively. Mice in each group was gavaged before one hour of the daily stress. The normal group and the model group were given physiological saline for a total of 21days.The behavior changes of body mass were observed by open field test in mice

and apoptosis of hippocampal neural cell morphology and cell DG area in mice brain tissue were observed by Nissl staining and TUNEL method. Result: Compared with the normal group

the body weight of model group was reduced(P<0.01)

the score of levels and vertical motion in the open field test were decreased in model group(P<0.01

P<0.05)

hippocampus neural cells in DG area was showed irregularly by Nissl staining and the number of apoptotic cells were increased

the difference of statistical was significance(P<0.01).Compared with the model group

the behavior score was improved in the Fluoxetine group and each daidzein group

the body weights of mice were increased(P<0.01)

the score of levels and vertical motion in the open field test were increased (P<0.01)

the changes of hippocampus were reduced. Conclusion: Daidzein can improve the behavior anomalie in mice who were induced by CUMS and have neuroprotective effect. The mechanism may be related to improving the nerve cell apoptosis.