Posterior reversible encephalopathy syndrome (PRES) is a neurotoxic state with distinct clinical and radiological features. It is characterized by headache, vomiting, altered mentality, seizures, and visual disturbances. PRES typically consists of reversible vasogenic edema in the posterior circulation territories, although irreversible cytotoxic edema and atypical lesion locations have also been described. Most patients are markedly hypertensive at presentation, although some have only mildly elevated or even normal blood pressure. Many known causative factors of PRES have been elucidated, but its underlying pathophysiology remains poorly defined. This review summarizes the etiologies, presumed pathophysiology, histopathologic findings, basic and advanced imaging features, clinical symptoms of presentation, and treatment of PRES.