In patients with hypertensive encephalopathy, brain edema is frequently distributed in the parieto-occipital white matter. We report a patient with high arterial blood pressure of over 300/160 mmHg on admission, who had extensive MRI-documented reversible lesions throughout the whole brain, including the brainstem, thalami, basal ganglia, and cerebellum. Extraordinarily severe acceleration of hypertension may be essential for the breakdown of autoregulation in the deep structures, especially in the brainstem including medulla.