Patients with a hemispheric infarct and massive space-occupying brain oedema 
have a poor prognosis. Despite intensive conservative treatment, the case 
fatality rate may be as high as 80%, and most survivors are left severely 
disabled. Non-randomised studies suggest that decompressive surgery 
substantially reduces mortality and improves the functional outcome of 
survivors. The 'Hemicraniectomy after middle cerebral artery infarction with 
life-threatening edema trial' (HAMLET) is a newly-conceived randomised 
multi-centre clinical trial that compares the efficacy of decompressive surgery 
to improve functional outcome with that of conservative treatment in patients 
with space-occupying supratentorial infarction.