Background: Studies evaluating traumatic brain injury (TBI) patients have shown an association between prehospital (PH) intubation and worse outcomes. However, previous studies have used surrogates, e.g., Glasgow Coma Scale (GCS) score ≤8 and Abbreviated Injury Severity Scale (AIS) score ≥3, which may overestimate the true presence of TBI. This study evaluated the impact of PH intubation in patients with PH GCS score ≤8 and radiographically proven TBI. Methods: Trauma patients routed to a Level I trauma center over a 3-year period with blunt injury and PH GCS score ≤8 were included. PH and in-hospital records were linked and head computed tomography scans were assigned a Marshall Score (MS). Patients with TBI (MS >1) were categorized into groups based on intubation status (PH, emergency department [ED], and no intubation). Comparisons were made using analysis of variance and χ statistics. Mortality differences, crude and adjusted risk ratios (RRs), and 95% confidence intervals (CIs) were calculated using proportions hazards modeling. Results: Of 334 patients with PH GCS score ≤8, 149 (50%) had TBI by MS. Among the TBI patients, 42.7% of patients were PH intubated, 47.7% were ED intubated, and 9.4% were not intubated during the initial resuscitation. Intubated patients had lower ED GCS score (PH: 4.1 and ED: 5.9 vs. 14.0; p < 0.0001) compared with patients not intubated. Also PH intubated patients had higher mean Injury Severity Score (38.0 vs. 33.7 vs. 23.5, p < 0.001) when compared with ED intubated and nonintubated patients. None of the nonintubated patients had a MS >2. Mortality for TBI patients who required PH intubation was 46.9% and 41.4% among ED-intubated patients. The crude RR of mortality for PH compared with ED intubation was 1.13 (95% CI, 0.68-1.89), and remained nonsignificant (RR, 0.68; 95% CI, 0.36-1.19) when adjusted for key markers of injury severity. CONCLUSIONS: Patients with PH GCS score ≤8 and proven TBI had a high overall rate of intubation (>90%). PH intubation seems to be a marker for more severe injury and conveyed no increased risk for mortality over ED intubation. Copyright © 2011 Lippincott Williams & Wilkins.