Brain swelling and intracranial hypertension following severe head injury are known to contribute to secondary brain damage, and have been shown to adversely affect patient outcome. The use of unilateral craniectomy following the evacuation of a mass lesion, such as acute subdural haematoma or traumatic intracerebral haematoma, is accepted practice. The following review focuses on a bi-fronto-temporal decompressive craniectomy, used as an isolated operation for the control of intracranial hypertension, secondary to diffuse brain swelling refractory to medical management. Though the operation is being increasingly used, current opinion is still divided regarding its overall effects on outcome. This review examines the experimental and clinical evidence for and against the use of decompressive craniectomy, highlights the lack of class I evidence relevant to this topic and emphasises the necessity for well-designed prospective randomised controlled trials.