Abstract: Objective To explore the association of blood and cerebrospinal fluid(CSF)IgG contents and the severity of craniocerebral injury.Methods Totalling 143 patients with craniocerebral injury were divided into 3 groups according Glasgow Coma Scale(GCS)scores,namely the mild injury group with GCS score of 12-15(n=41),moderate injury group with GCS score of 9-11(n= 71)and severe injury group(GCS score 3-8,n=32).Another 9 patients with congenital hydrocephalus were also recruited as the control group.The CSF and blood samples were collected from these patients to measure the IgG contents 4 and 14 days and 1,2,and 6 months after the injury,respectively.Physical disabilities of the patients were estimated with Rappaport’s disability rating scale(DRS),whose correlations with CSF and blood IgG contents were analyzed.Results In the early stage of moderate to severe brain injury,the IgG content was lowered significantly in the blood but increased in CSF as compared with the control patients(P<0.05),and the changes in CSF and blood IgG displayed a significant correlation with the severity of the injury(r=0.950,P<0.01).During the recovery of severe brain injury,DRS score was in inverse correlation with blood IgG content but in positive correlation with CSF IgG content(Spearman’s correlation coefficient of 0.800,P<0.05).Conclusion In the early stage of brain injury,detection of blood IgG content may help with the assessment of the injury severity.During the recovery of the injury,dynamic monitoring of blood and CSF IgG contents provides clues of the outcome of the patients and benefit the modification of the treatment plan.