1) An attempt was made to study variation of cholinesterase and free nitrogen of aminoacids at globus pallidus lesion produced by various methods, such as oil-wax-, etopalin-injections and electrical coagulation. Eight normal cats for each these three groups were utilized in this study. 2) Both cholinesterase and free nitrogen of aminoacids were decreased in value for the first postoperative week in case of the oil-wax injection. They would, however, both come back to the normal values within the third postoperative week. 3) In case of the etopalin injection, the values of both cholinesterase and free nitrogen of aminoacids were considerably decreased for the first postoperative week and would not come back to the normal values within the third postoperative week. 4) The electrically coagulated lesion manifested the same tendency of the variation of the two substances as the oil-wax method for the first week. However, the recovery is comparatively sharp in contrast to the latter.