In the experiments in the Part Ⅰ, it has been clarified that GABOB has an inhibitory action to the cerebral cortex and may apply directly on the cerebral cortex without side effect. In this Part Ⅱ, a clinical study has been performed on administration of GABOB into the cerebro-spinal fluid cavity. One is the application of GABOB to the intradural cavity during craniotomy of brain tumor to prevent the postoperative convulsions, and the other is the intrathecal and intraventricular administration of GABOB when postoperative convulsions occur. For the purpose of preventing the postoperative convulsions after craniotomy, 100 mg of GABOB was applied on the cerebral surface during craniotomy in 293 cases of brain tumor. Except for operative deaths, a comparison of the postoperative convulsions was made between the GABOB group and the control group. 1) The occurrence of postoperative convulsions was decreased in the GABOB group. 2) In the GABOB group, the onset of postoperative convulsions was later than that of the control group. 3) Frequency of postoperative convulsions was decreased in the GABOB group, and majority of the cases showed only one seizure. 4) Administration of GABOB into the intradural cavity showed no side effect. There were 14 cases of postoperative convulsive state. Application of GABOB into the intraventricular or intrathecal cavity was effective to inhibit convulsive state in all cases without any side effect. From the these results, it is recognized that application of GABOB into the cerebro-spinal fluid cavity is most effective method to the prevention and treatment of the postoperative convulsions.