OBJECTIVE The purpose of this study was to investigate the findings on spin-echo and gradient-echo MR images obtained in patients with hypertensive encephalopathy. METHODS The MR images of 36 patients with clinically documented acute (< 72 hr) hypertensive encephalopathy were prospectively examined. Brain swelling on short TR images, hyperintensity on long TR images, and hypointensity on long TR and gradient-echo images were assessed. RESULTS The most common finding was hyperintensity in the supratentorial white matter (n = 32), representing hypertensive encephalopathy-induced reversible edema, irreversible infarction, or preexisting ischemic disease. These entities were difficult to distinguish on the basis of the initial examination. A more characteristic finding was edema (swelling on short TR images and hyperintensity on long TR images) in the basal ganglia (n = 22), brainstem (n = 15), and cerebellum (n = 11). Punctate foci of hypointensity, seen on long TR spin-echo images but optimally visualized on gradient-echo images, were the most distinguishing feature of this disorder. CONCLUSIONS MR imaging is efficacious in revealing deep ganglionic and posterior fossa edema, which is characteristic of hypertensive encephalopathy. Serial MR studies are necessary to distinguish transient edema from permanent zones of infarction. Gradient-echo MR imaging is particularly valuable in visualizing petechial hemorrhages, the presence of which distinguishes nonspecific white matter disease from an acute or prior episode of hypertensive encephalopathy and serves as a permanent marker of this disease.