Trauma is one of the most common causes of morbidity and mortality in modern society, and traumatic brain injuries (TBI) are the single leading cause of mortality among young adults. Pre-hospital acute care management has developed during recent years and guidelines have shown positive effects on the pre-hospital treatment and outcome for patients with severe traumatic brain injury. However, reports of impacts on improved nursing competence in the ambulance services are scarce. Therefore, the aim of this study was to investigate if increased nursing competence level has had an impact on pre-hospital assessment and interventions in severe traumatic brain-injured patients in the ambulance services.