Objective To investigate the correlation between Glasgow coma scale (GCS) and bispectral index (BIS) in adults with acute brain injury, and explore the feasibility of BIS value in assessment of brain injury. Methods The prospective and double-blinded design was adopted, and the GCS and BIS values of 89 adults were collected. The mean BIS values of patients with different severity of brain injury were calculated. Linear regression between BIS value and GCS value was constructed, and receiver operating characteristic (ROC) curves at GCS <9 or <13 were plotted respectively. Results There were significant differences in BIS values among patients with mild, moderate and severe brain injury (81.29±7.29, 69.32±8.50 and 45.79±12.39 respectively, P<0.01). There was a significantly

positive correlation between GCS value and BIS value (R²=0.825, P<0.01). The regression equation was BIS=4.23×GCS+22.22. The ROC curve at GCS<9

demonstrated that the area under the curve (AUC) was 0.963, and the cut-off point (BIS value) corresponding with the maximum sensitivity (0.932) and

specificity (0.933) was 63.8.The ROC curve at GCS score<13 demonstrated that AUC was 0.933, and the cut-off point (BIS value) corresponding with the

maximum sensitivity (0.905) and specificity (0.851) was 71.6. Conclusion BIS value significantly correlates with GCS value in adults with acute brain

injury. As a continuous, real-time and objective parameter, BIS can be used as a new tool to assess and monitor the severity of brain injury.