Abstract: Objective: To observe the effects of two different doses of naloxone on Bispectral index(BIS) in patients with severe craniocerebral injury,explore the clinical curative effects of different doses of naloxone,and evaluate the feasibility of the BIS in judging the prognosis of patients with severe craniocerebral injury.Methods: Fifty-five adult patients with severe craniocerebral injury were divided into the control group(18 cases),low-dose naloxone group(group A,18 cases) and high-dose naloxone group(group B,19 cases) according to the admission time.The control group were treated with routine method.The groups A and B were treated with 0.1 mg·kg^-1·d^-1 and 0.4 mg·kg^-1·d^-1 naloxone based on the routine method for 14 days.The BIS value in groups A and B were recorded during treatment,and the scores of Glasgow Outcome Scale(GOS) in groups A and B were measured after 1 month of treatment.Results: The differences of the BIS value between three groups were not statistically significant in the first day of admission(P>0.05),and the BIS value in groups A and B after 14 days of admission increased significantly compared with that in the first day of admission(P<0.01).The increasing degree of BIS value after 14 days of admission in group B was significantly higher than that in control group and group A(P<0.01).The scores of GOS in groups A and B were significantly higher than that in control group(P<0.01),and the score of GOS in group B was significantly higher than that in group A after 1 month of admission(P<0.01).The BIS value of patient was significantly positive correlation with the GOS score after 14 days of admission(P<0.01).The differences of the mortality after 1 month of treatment between 3 groups were not statistically significant(P>0.05).Conclusions: The treatment of the severe craniocerebral injury with early large dose naloxone can improve the nerve function,but which can not reduce the mortality of patients.The effect of BIS in evaluating the degree of brain damage and prognosis is good.