The biological activities of fruits of Poncirus trifoliata have been studied. 70% Ethanol extract of Ponciri Fructus was fractionated with ether, ethyl acetate and n-butanol by turns. The ether fraction showed antibacterial activity on Staphylococcus aureus and inhibited the contractability of the isolated mice ileum. The ethyl acetate and n-butanol fractions showed the anti-edematous effect on the carrageenin-induced edema of rat hindpaw. From the n-butanol fraction, one of the flavonoid glycoside was isolated and identified as poncirin. Ponciri Fructus contained about 6% poncirin which was 5,7-dihydroxy-4´-methoxy flavanone rhamnoglucoside and poncirin showed antiinflammatory activities. Poncirin was considered as the major effective component of Ponciri Fructus.