The effects of extracts from various oriental medicinal herbs on mast cell-mediated allergic reaction were investigated. Among them, Chrysanthemi sibirici herba ethanol extract exerted the potent inhibitory activity on antigen-induced degranulation in RBL-2H3 mast cells. Chrysanthemi sibirici herba dose-dependently inhibited DNP-BSA or compound 48/80-induced degranulation in RBL-2H3 mast cells, with IC(50) values of approximately 49 microg/ml and 76 microg/ml, respectively. This extract strongly suppressed compound 48/80-induced systemic anaphylaxis by 48.7% at a dose of 300 mg/kg in mice. Chrysanthemi sibirici herba also inhibited the expression of TNF-alpha and the activation of the MAP kinase, ERK1/2, which is critical for the production of inflammatory cytokines in mast cells, as indicated by the suppression of activating phosphorylation of ERK1/2. These results lead us to conclude that Chrysanthemi sibirici herba may be used clinically to treat various allergic diseases.