With the brain extracted from the anesthetized mice or the mice with experimental convulsion, the glutamic decarboxylase activities of the brain were measured and the following results were obtained. 1. Anesthesia by ether or phenobarbital does not affect the glutamic decarboxylase activity of the brain. 2. Anesthesia by metrazol shows a slight decrease in the glutamic decarboxylase activity but it is not significant. On the other hand, the glutamic decarboxylase activity is decreased in the brain of the animal given electroshock.