The effect of seventy kinds of medicinal plants on the activities of GABA-metabolizing enzymes as glutamate dehydrogenase I (GDH I), glutamate dehydrogenase II (GDH II), GABA transaminase (GABA-T), succinic semialdehyde dehydrogenase (SSADH) and succinic semialdehyde reductase (SSAR) were estimated. The following plants extracts from Acori graminei Rhizoma, Longnae Arillus, Gastrodiae Herba, Lycii Fructus, Ligusticum officinale, Ferula assafoetida, Corydalis Tuber, Eucommiae Cortex, Zizyphi spinosi Semen activated the activity of GDH I to more than 35%, and the following ones from Visci Ramulus, Ligusticum officinale, Myristicae Semen, Ferulae Resina, Scolopendrae Corpus, Corydalis Tuber, Eucommiae Cortex, Zizyphi spinosi Semen did that of GDH II. The plant extracts from Cynanchi Radix, Astragali Semen, Angelicae dahuricae Radix, Biotae orientalis Folium, Uncariae Ramulus et Uncus, Polygalae Radix, Cynomorii Herba inhibited that of GABA-T to 35% and over, and the following ones from Hyoscyamus niger, Cynanchi Radix, Acori graminei, Caesalpiniae Lignum, Cannabis Semen, Sedum aizoon, Sedum kamtschaticum, Schisandrae Fructus, Lilii Bulbus, Biotae orientalis Folium, Uncariae Ramulus et Uncus, Myristicae Semen, Akebiae Fructus, Cynomorii Herba, Buddleiae Flos, Mucunae Caulis, Zizyphi Fructus, Paeoniae Radix rubra did that of SSADH to 70% and over; the following ones from, Caesalpiniae Lignum, Sedum kamtschaticum, Schisandrae Fructus, Astragali Semen, Angelicae dahuricae Radix, Dioscorea nipponica, Myristicae Semen, Akebiae Fructus, Cynomorii Herba, Scutellariae Radix did that of SSAR.