Objective: To investigate the antidepressant effect of extracts of the water (HZ-W) and 75% ethanol (HZ-E) from rhizome of Polygonum cuspidatum Sieb. et Zucc. Method: Mice were treated with HZ-W(1.5

3 g·kg-1)

HZ-E(1.5

3 g·kg-1)

and fluoxetine hydrochloride (FH

10 mg·kg-1) everyday for seven consecutive days by intragastric administration (ig). The mouse forced swim test (FST)

tail suspension test (TST) and open field test (OFT)

were used to observe antidepressant activities of HZ-W and HZ-E

respectively

at 1 h after the last administration. Result: The immobility time of TST and FST in model mice was (95.83±17.18)

(126.00±20.79) s respectively and there was significant decrease among HZ-W(1.5

3 g·kg-1)

HZ-E(3 g·kg-1)

FH(10 mg·kg-1) groups compared with model group. The numbers of crossing squares in 3 min in model mice during OFT were (88.44±19.22)

and there was no significant difference among HZ-W

HZ-E

FH groups compared with model group. Conclusion: The present study firstly indicates that HZ-W and HZ-E exerts antidepressant activity and the former is more potent than the latter at the same dose.