The use of the Glasgow Coma Scale may be limited by the experience of physicians, errors resulting from subjectivity, the inability of patients to respond, and discontinuity. This study demonstrates that the Bispectral Index scores correlate well with scores from the Glasgow Coma Scale and that Bispectral Index scores can provide real-time, objective, and continuous monitoring of the consciousness level of critically ill children. Sixteen patients with consciousness disturbance, who were admitted to a pediatric intensive care unit of a tertiary university-affiliated children's hospital, were enrolled in this study. The patients received 34 Glasgow Coma Scale assessments and Bispectral Index scores. The age of patients ranged from 10 to 192 months (mean +/- S.E. = 68.4 +/- 12.3 months). Glasgow Coma Scale ranged from 3 to 11 (mean +/- S.E. = 6.3 +/- 0.4), and Bispectral Index score ranged from 0 to 100 (mean +/- S.E. = 55.4 +/- 5.6). A positive correlation was found to exist between Glasgow Coma Scale and Bispectral Index score (r = 0.76, P < 0.001). In conclusion, the Bispectral Index score correlates well with the Glasgow Coma Scale in critically ill children who score between 3 and 11 on the Glasgow Coma Scale.