Abstract： Objective To explore the most effective daily dose and use method of mannitol in reducing intracranial pressure in patients with cerebral hemorrhage in acute stage.Methods One hunred and eighteen cerebral hemorrhage patients with elevated intracranial pressure,74 males and 44 females,aged(58±11)(33-80),that had undergone cranial CT scanning to calculate the volume of hemorrhage,were divided into 4 groups treated with 20%mannitol 125 ml:32 cases treated q 4 h,35 cases treated q 6 h,25 cases treated q 8 h,and 26 cases treated q 12 h.The everyday doses of mannitol were recorded.Intracranial pressure was monitored daily by NIP-200 noninvasive intracranial pressure aDparatus.The difference between the very day and that of the last day(effect of decreasing intracranial pressure per day)was calculated.Multivariate regression analysis was conducted.Results The average saturation dosage of mannitol was 750-6000(3504±1085)ml,the time from the hospitalization till the saturation dosage was 1-8(4.5±1.5)d.The average intracranial pressure at admission was 330-698(486±93)mm H2O,the average intracranial pressure when mannitol reached the saturation dosage was 160-378(253±52)mm H2O.The effect of reduction of intracranial pressure was not associated with age(P＞0.05).The effects of reducing intracranial pressure in the 1st,2nd,3rd,and 4th day were associated with the volume of hematoma and mannitol doses(all P＜0.01).Best effects of reducing the intracranial pressure in the 1st,2nd,3rd,and 4th day could be reached when 20% mannitol 125 ml was used every 4 hours.Conclusions Mannitol use every 4 hours per day has evident effect of reducing the intracranial pressure in the 1st,2nd,3rd,and 4th day,then mannitol should be used temporarily according to the intracranial pressure after the 5th day,Mannitol should not be used for more than 8 days.