Pharmacological properties of the extracts from the magnolia cortex (the bark of Magnolia obovata THUNB.) were examined with special reference to their central nervous system action. The ether extract of the magnolia (1g/kg i.p.) markedly depressed the spontaneous activity of mice and chicks, while the water extract (1g/kg i.p.) procuced prompt paralysis of respiration. Distinct muscle weakness was found after administraction of the ether extract, through the clinging power test on the wire net, and was different from the effect of the water extract. The ether extract supressed convulsion produced by strychnine, picrotoxin, or pentetrazol. Tremor by oxotremorine was also blocked by the ether extract. Pentetrazol infusion technique was employed for the elucidation of the mode of this drug action. Depressive effect of the ether extract was also exerted on the crossed extensor reflex of the chick spinal cord.