Objective: To screen the antidepressant fractions from Cyperus rotundus and investigate the possible a mechanism. Method: The extract and florentine were orally given to mice at a dosage of 10 g·kg-1 and 0.08 g·kg-1 per day

respectively. The swimming test and the tail suspension test were applied to observe the antidepressant effect of C. rotundus extracts. The content of serotonin(5-HT)

dopamine(DA) and noradrenalin(NE) was determined by RP-HPLC method to study the mechanism of C. rotundus extracts. Result: The ethyl acetate and n-butanol fractions from the ethanol extract of C.rotundus significantly shortened immobility time in swimming test and the tail suspension test. The ethyl acetate and n-butanol fractions from the ethanol extract of C.rotundus markedly increased the content of 5-HT and DA with no action of NE. Conclusion: The ethyl acetate and n-butanol fractions from the ethanol extract of C.rotundus can produce an antidepressant effect

the mechanism of which may be related to affecting the 5-HT and DA nervous system. They may be the active part of C.rotundus.