Objective: To screen the antidepressant effects of different fractions from Xiao Chaihu decoction. Method: Male Kunming mice were randomly divided into 10 groups:control group

fluoxetine and the petroleum ether extract (part Ⅰ)

ethyl acetate extract (part Ⅱ)

butanol extract water saturated butanol extract (part Ⅲ) and residual water layer extract (part Ⅳ) of the Xiao Chaihu decoction. The treatment groups received part Ⅰ-Ⅳ at dose of 9.0

18.0 g·kg-1 and fluoxeine at 20 mg·kg-1 for 7 days respectively. The tail suspension test (TST) and forced swimming test (FST) were carried out to compare the antidepressant effects of different fractions from Xiao Chaihu decoction at 1 hour after the last administration. Result: The group of part Ⅱand part Ⅲcould significantly shorten mice immobility time in FST and TST(P<0.05 or P<0.01). Conclusion: The antidepressant pharmacodynamic tests shows that ethyl acetate extract and butanol extract can be initially determined as the antidepressant effective fraction of Xiao Chaihu decoction.