OBJECTIVE: The objective was to compare the accuracy of the pediatric Glasgow Coma Scale (GCS) score in preverbal children to the standard GCS score in older children for identifying those with traumatic brain injuries (TBIs) after blunt head trauma. METHODS: This was a planned secondary analysis of a large prospective observational multicenter cohort study of children with blunt head trauma. Clinical data were recorded onto case report forms before computed tomography (CT) results or clinical outcomes were known. The total and component GCS scores were assigned by the physician at initial emergency department evaluation. The pediatric GCS was used for children <2 years old and the standard GCS for those >/=2 years old. Outcomes were TBI visible on CT and clinically important TBI (ciTBI), defined as death from TBI, neurosurgery, intubation for more than 24 hours for the head injury, or hospitalization for 2 or more nights for the head injury in association with TBI on CT. We compared the areas under the receiver operating characteristic (ROC) curves between age cohorts for the association of GCS and the TBI outcomes. RESULTS: We enrolled 42,041 patients, of whom 10,499 (25.0%) were <2 years old. Among patients <2 years, 313/3,329 (9.4%, 95% confidence interval [CI] = 8.4% to 10.4%) of those imaged had TBIs on CT and 146/10,499 (1.4%, 95% CI = 1.2% to 1.6%) had ciTBIs. In patients >/=2 years, 773/11,977 (6.5%, 95% CI = 6.0% to 6.9%) of those imaged had TBIs on CT and 572/31,542 (1.8%, 95% CI = 1.7% to 2.0%) had ciTBIs. For the pediatric GCS in children <2 years old, the area under the ROC curve was 0.61 (95% CI = 0.59 to 0.64) for TBI on CT and 0.77 (95% CI = 0.73 to 0.81) for ciTBI. For the standard GCS in older children, the area under the ROC curve was 0.71 (95% CI = 0.70 to 0.73) for TBI on CT scan and 0.81 (95% CI = 0.79 to 0.83) for ciTBI. CONCLUSIONS: The pediatric GCS for preverbal children was somewhat less accurate than the standard GCS for older children in identifying those with TBI on CT. However, the pediatric GCS for preverbal children and the standard GCS for older children were equally accurate for identifying ciTBI.