Neurosurgical therapy aims to minimise the secondary brain damage after a severe head injury. This includes the evacuation of an intracranial space occupying bleeding, the reduction of intracranial volumes, in hematocephalus an external ventricular drainage, and the conservative therapy in order to influence an increased intracranial pressure (ICP) and a decreased p(ti)02. When conservative treatment fails to act a decompressive craniectomy might be successful in lowering ICP. From September 1997 until July 2004 we operated on 737 patients with severe head injuries. 103 patients (14%) were treated by means of a decompressive craniectomy. The prognosis after decompression depends on the clinical signs and symptoms on admission, the patients age and the existence of major extracranial injuries. Our guidelines for an indication for decompressive craniectomy after failure of conservative interventions and evacuation of space occupying hematomas include a patients age below 50 years without multiple trauma, a patients age below 30 years in the presence of major extracranial injuries, a severe brain swelling on CT scan, the exclusion of a primary brainstem lesion or injury and the intervention before irreversible brainstem damage and secondarily while monitoring ICP and p(ti)02 in an interval up to 48 hours after the accident before irreversible brainstem damage or generalised brain damage has occurred.