The present study was undertaken to investigate the effect of electroacupuncture (EA) on electroconvulsive shock (ECS) and penicillin-induced convulsions in rats, using power spectrum analysis technique. Under quiet state, delta and theta bands were found to be predominant in the power spectrum of spontaneous EEG's with the peak of the main power in the delta band. During ECS and penicillin-induced convulsions, the power percentage of the delta band decreased, while those of alpha and beta bands increased. The bands with the peak of the main power shifted to the right, and the total power was distinctly enhanced. No marked change in background EEG activity was observed during EA stimulation. In the case of EA plus ECS or penicillin-induced convulsions, the power percentage of the delta band increased, while those of alpha and beta bands decreased. The peak of the main power returned to the delta band with a decreased total power. The compressed power spectrum array showed distinct suppression of convulsions by EA audio-visually. These results suggest that EA enables the EEG to synchronize and enhances the inhibitory process of the brain, thereby plays its anticonvulsant role.