The chloroform and the ethyl acetate fractions from the roots of Acanthopanax chiisanensis exhibited a significant inhibition of prostaglandin E$_2$ (PGE$_2$）production in rat peritoneal macrophages stimulated by the protein kinase C activator, 12-O-tetradecanoylphorbol 13-acetate （TPA）. Hyperin was isolated as an active principle from the ethyl acetate fraction. It sup-pressed not only $PGE_2$ production but also nitric oxide （NO） production in vitro in a concentration dependent manner. their $IC_{50}$, being 24.3 and $32.9{;}{mu}M$, respectively. Hyperin also caused a significant inhibition of increase in acetic acid-induced vascular permeability in mice in vivo.