Morinda officinalis (MO) is a oriental medicinal herb which has been used traditionally for the treatment of impotence, anti-inflammatory, menstrual irregularity action and various brain diseases including antidepressant and anti-stress. In order to examine the mechanism of anticonvulsive effect, we treated the methanol extract of MO (100, 200 mg/kg, P.0) to the sleeping time and pentylenetetrazol (PTZ)-induced convulsive mice. The methanol extract of MO prolonged sleep time by pentobarbital. Dose-dependent of methanol extracts of MO were effected the concentration of GABA and GABA-T activity in the brain of PTZ-induced mice. Methanol extracts of MO significantly inhibited the convulsion state as well as the level of lipid peroxidation in the brain. The butanol and dichloromethane fraction of methanol extracts among the others effectively inhibited in vitro lipid peroxidation dose dependently ($5.0{ imes}10^{-2}{sim}20.0{ imes}10^{-2}g/ml$).