This review summarises the current knowledge of posterior reversible encephalopathy syndrome which is an acute and severe neurological condition characterised by headache, encephalopathy, epileptic seizures, and visual disturbances. Typical radiological findings are cerebral vasogenic oedema, predominantly localised in the posterior cerebral circulation. The exact pathophysiological mechanisms remain unknown but involve dysfunction of the blood-brain barrier. There are several well-documented causes for the syndrome, the most important being acute hypertension. Management is aimed at identifying and eliminating the underlying cause and preventing secondary brain injury from, e.g., epileptic seizures.