Using an experimental apparatus for estimating neurotransmitter release from brain slices, which involved an improved type of perfusion chamber and more well-controlled tube lines than the previous one were aspartic acid and γ-aminobutyric acid (GABA) release from hippocampal slices from epileptic E1 mice estimated more exactly and stably. Zonisamide had no effect on the aspartic acid release from hippocampal slices of E1 mice by zonisamide. However, zonisamide accelerated dose dependently GABA release from hippocampal slices of non-stimulated E1 mice, though no such acceleration was observed in stimulated E1 mice, i. e., repeatedly convulsed E1 mice.