Patients with intracranial haematoma following head injury may have little primary brain injury, but sustain a secondary brain injury that can often be minimized by early evacuation of the haematoma. Rapid intervention by a neurosurgeon with early evacuation of the haematoma gives a better outcome. The timing of treatment in 403 patients with severe head injuries, admitted to the Royal London Hospital between January 1991 and December 1994 was examined. All cases had been transported directly from the accident scene by the Helicopter Emergency Medical Service because the local hospital did not have neurosurgical facilities. The median time to medical intervention was 15 min (95 per cent, confidence interval (CI) 14-16) and the median time to neurosurgery was 177 min (95 per cent, CI 171-195). As secondary interhospital transfer of patients with head injuries is known to increase the time to neurosurgical intervention and is a time of great risk of secondary insult to the brain, transfer direct from the scene of the accident to an appropriate centre allows a process of care that has been shown to be associated with a better outcome.