Hypertensive disorders of pregnancy are a major cause of maternal mortality and morbidity. Preeclampsia and eclampsia are among the most common causes of posterior reversible encephalopathy syndrome (PRES). Clinically, PRES is characterised by visual disturbances, headache, nausea, change in mental status and seizure. Although treatment of the underlying cause provides clinical and radiological healing, a delay in the diagnosis and treatment can result in permanent brain damage and death. The exact incidence of new-onset postpartum hypertension is difficult to ascertain. Women with mild hypertension are usually asymptomatic; therefore, patients either can not be diagnosed or are diagnosed with late complications. With this case, we would like to present a patient who had no diagnosis of maternal hypertension or preeclampsia-eclampsia during pregnancy but, after a postpartum seizure, was diagnosed with PRES.