Worldwide 50 million people have a traumatic brain injury (TBI) each year.1 It is the leading cause of death in young adults, causes considerable morbidity and has a huge cost to society. Prevention through public health programmes is key; however, once primary injury has occurred, it is our job as clinician/scientists to minimise neuronal loss through secondary brain injury. The time to do this is as early as possible in the pathogenesis of neuronal injury and hence the pre-hospital phase is the most critical of all. The quality of pre-hospital care varies considerably globally – from non-existent through to advanced clinician led, often helicopter-based services that can perform multiple interventions. This chapter will explain the basic processes in the first few hours after TBI and interventions that can be used to minimise secondary injury.