Hypertensive encephalopathy is a severe complication of hypertensive crisis or malignant hypertonia. We report a case with grave clinical and radiological features. The patient was comatose, with pupillary dysfunction, and initial CT suggested a local intracranial mass with edema. Cranial MRI showed almost completely hyperintensive supratentorial white matter, with edema and midline shift, and hypertensities in cerebellum and brainstem. The patient recovered, and the radiological findings improved after antihypertensive therapy. Hypertensive encephalopathy may be differentiated by MRI, manifests acutely, and is potentially reversible when adequate therapy is rapidly performed.