Continuous monitoring of intracranial pressure (ICP) is now an accepted part of neurosurgical practice, used in the management of patients with severe head injury, coma-producing subarachnoid haemorrhage, hydrocephalus, intracranial infection and following hypoxic or ischaemic insults to the brain. The pressure is measured from the lateral ventricle or from the subarachnoid space, and each neurosurgical department should establish criteria for determining what level of increased ICP should be acted upon and how it should be managed. This review favours a three stage approach: a) determining that ICP is truly elevated and correcting any immediately remediable causes, such as airway obstruction, then b) first-line measures, which consist of hyperventilation, osmotherapy and controlled CSF drainage, then c) second-line measures, consisting of short-acting anaesthetic agents--thiopentone and gammahydroxybutyrate. Future refinements of ICP monitoring will include improved understanding and better methods of measuring intracranial pressure-volume relationships and more detailed analysis of intracranial pulse pressure and the pressure waveform, its changes with mean ICP and its relationship with the arterial pressure waveform.