This chapter discusses the diagnosis, evaluation and management of severe traumatic brain injury (TBI). Early intubation is indicated in all severe TBI patients, and pretreatment may help minimize increase in intracranial pressure (ICP) during intubation. All severe TBI patients should have a neurosurgical evaluation early in their ED course. If the patient has a seizure, treatment and loading with 1g of phenytoin or fosphenytoin is indicated. The decision to place invasive ICP monitoring should generally be made in conjunction with neurosurgery. The indications for invasive ICP monitoring (external ventricular drain or intraparenchymal monitor) include severe TBI and a computed tomography (CT) showing hematomas, contusions, swelling, herniation, or compressed basal cisterns. Propofol or pentobarbital coma may be induced for severe, but nonsurgical TBI. The goal is to reduce cerebral activity and oxygen demand. These agents cause hypotension and decreased cerebral perfusion pressure (CPP) and should only be initiated with neurosurgical input.