OBJECTIVE: The aim of this retrospective study was to externally validate the CRASH (Corticosteroid Randomisation After Significant Head Injury) clinical calculator as a prognostic tool. Mortality at 14 days and an unfavorable outcome (i.e., Glasgow Outcome Scale score <4) after 6 months were the primary endpoints. METHODS: The study included adult patients admitted to the emergency department of Ghent University Hospital during 2010-2014 with traumatic brain injury. The CRASH score was calculated for every patient and compared with real-life outcome at 14 days and 6 months. Researchers were blinded for each other's results, and each observer either calculated the CRASH score or obtained clinical outcome. Receiver operating characteristic analysis was used to validate the CRASH calculator. The prognostic value of other variables was tested using logistic regression (P < 0.05 was significant). RESULTS: Of 417 included patients with traumatic brain injury, 94.7% were still alive at 14 days, and 65% had a Glasgow Outcome Scale score >= 4 at 6 months. Receiver operating characteristic analysis showed an area under the curve of 92.1% at 14 days and 90.7% at 6 months (P< 0.05). Calculated cutoff value for the CRASH score at 14 days was 31.50% (sensitivity 0.823, specificity 0.895). At 6 months, calculated cutoff value was 55.75% (sensitivity 0.793, specificity 0.830). CONCLUSIONS: The CRASH calculator is a good predictor of outcome in traumatic brain injury at 14 days and 6 months with high sensitivity and specificity. It does not replace clinical judgment of the physician treating the patient in the emergency department, but it constitutes a useful additional tool.