In order to inquire the most-effective management of increased intracranial pressure(ICP), mannitol, steroid and hyperventilation were used in rabbits after ligation or non-ligation of the carotid artery. Mannitol was more effective than steroid and hyperventilation in the degree of the reduction of ICP. The intracranial pressure was decreased 43~45% for 25~30 minutes after injection of mannitol. Steroid was less effective than mannitol in the degree of the reduction of ICP. But the time of reduction of ICP was longer, that is, the degree of reduction was 24~60 minutes after injection of steroid. Hyperventilation is effective in the initial time only, for 10 minutes after hyperventilation. The degree of ICP reduction was 13.5~16.7 % for 10 minutes after hyperventilation. The combined group, that is three kinds of mangenent were used, is the most effective treatment to reduce ICP of ICP. The degree of the reduction of ICP was 42.1~49.3% for 20 minutes, 47.7~52.5% for 30minnutes. There was no significant difference between and non-ligation group.