The effect of aqueous extract of Magnoliae Cortex (Magnoliaceae) (MCAE) on the immediate-type allergic reaction was investigated. MCAE inhibited compound 48/80 induced systemic anaphylactic reaction in rats. MCAE (0.1 and 1 g/kg) also significantly inhibited local immunoglobulin E (lgE)-mediated passive cutaneous anaphylactic (PCA) reaction. MCAE (0.001 to 1 mg/ml) dose-dependently inhibited the histamine release from rat peritoneal mast cells (RPMC) activated by compound 48/80 or anti-dinitrophenyl (DNP) 1gE. Moreover, MCAE (0.01 to 1 mg/ml) had a significant inhibitory effect on anti-DNP IgE-mediated tumor necrosis $factor-{alpha}$ $(TNF-{alpha})$ production. These results indicate that MCAE inhibits immediate-type allergic reaction in vivo and in vitro.