Abstract: Background: In prehospital setting, a severe traumatic brain injury (TBI) requires tracheal intubation, sedation and mechanical ventilation pending the initial imagery. An early neurological wake-up test (ENWT), soon after the initial imaging assessment, allows a rapid neurological reassessment. This strategy authorises an initial clinical examination of reference with which will be compared the later examinations. Objective: The main objective of this study was to describe the characteristics of the patients who underwent an ENWT, and to determine its causes of failure. Methods: We conducted a retrospective, observational, single-centre study including all intubated TBI admitted in the trauma centre. An ENWT was defined as cessation of sedation within 24 h after TBI. Data concerning patient characteristics, CT-scan results, and outcomes were extracted from a prospective register of all intubated TBI admitted in the ICU. Characteristic of ENWT and causes of failure were retrieved from patient files. A multivariate logistic regression model was developed to determine the risk factors of ENWT failure. Results: During 7 years, 242 patients with intubated TBI were included. An ENWT was started in 96 patients, for an overall rate at 40%. The ENWT was stopped in 38 patients (39.5%), mostly due to neurological deterioration in 27 cases (71%) or respiratory distress in 10 cases (26%). Significant predictors of ENWT failure were: the presence of subdural hematoma with a thickness >5 mm on first imagery (OR=3.2; 95%CI [1.01-10.28]), and an initial GCS score <5 (OR=7.4; 95%CI [1.92-28.43]). Prevalence of poor outcome at 1 year was lesser in patients with successful ENWT compared to those with failure or absence of ENWT: 4% vs. 48% and 49% (P<0.0001). Conclusion: The ENWT is achieved in 40% of patients, with a success rate of 60.5%. In presence of a subdural hematoma with a thickness >5 mm or an initial GCS score <5, an ENWT failure may be expected.