Posterior reversible encephalopathy syndrome (PRES) is a neurotoxic clinico-radiological diagnosis typically presenting with headache, encephalopathy and visual disturbance accompanied by a unique neuroradiological pattern of symmetrical parieto-occipital vasogenic oedema. Here we present the case of a 51-year-old woman who presented to hospital following a thunderclap headache, initially thought to be secondary to a subarachnoid haemorrhage (SAH). A tiny anterior choroidal artery aneurysm was demonstrated on cerebral angiogram. At surgical clipping, no evidence of haemorrhage was observed. Post-operatively, the patient developed delayed right-sided hemiparesis, managed with aggressive hypertensive treatment, and later, with onset of septicaemia, central visual loss. Computed tomography (CT) brain scans demonstrated oedematous changes within the parieto-occipital regions bilaterally and later areas of infarction. The initial diagnosis of SAH was revised to reversible cerebral vasoconstriction syndrome (RCVS), which gave rise to PRES. To our knowledge, this is the first reported case of RCVS with concomitant PRES and cerebral infarction.