Posterior reversible encephalopathy syndrome (PRES) affects predominantly the parietal and occipital lobes. Frequent clinical features are epileptic seizure, altered mental status and visual disturbances.We present the first case of a patient with pericarditis and mitral valve insufficiency, who developed PRES after application of a glycerolnitrate patch day three post-operatively and whose neurological deficits improved within 2 days after withdrawal of patch therapy.The precise pathomechanism of PRES is unknown. The lower sympathetic innervation of the posterior circulation may be one explanation for its particular vulnerability to vasodilatation caused by glycerolnitrate.