Reversible posterior leukoencephalopathy is a syndrome of headache, seizures and visual loss, often associated with an abrupt increase in blood pressure. Prompt diagnosis and therapy with antihypertensives, anticonvulsants, removal of any offending medication and treatment of associated disorders is essential since early treatment might prevent progression to irreversible brain damage. We present six illustrative cases presenting to Christchurch Hospital and review the condition. All were hypertensive, two were receiving immunosuppressant therapy after transplantation and one chemotherapy. Only three made a full recovery. The term reversible posterior leukoencephalopathy is a misnomer as the condition is not always reversible, is not necessarily confined to the posterior regions of the brain and can affect both white and grey matter. Magnetic resonance imaging findings of increased T2 and fluid attenuated inversion recovery signal predominantly involving the posterior regions of the cerebral hemispheres should alert the clinician to the possibility of this diagnosis.