Posterior reversible encephalopathy syndrome (PRES) is an uncommon neurological disorder, characterised by the rapid onset of neurological deficits and characteristic neuroimaging findings-cerebral oedema with a typical preference for the posterior white matter. We report a case of a 59-year-old woman with an untreated HIV infection and hypertension with a PRES diagnosis and a rare involvement of the basal ganglia and brainstem, with microhemorrhages. HIV infection, particularly if untreated, is associated with an inflammatory status and therefore endothelial damage and dysfunction that might have an important role in predisposing acute hypertensive crisis and PRES.