A 48-year-old man was admitted due to sudden disorientation and dysarthria. He has been drinking almost everyday for the past 25 years. At the time of the admission, he was alert but confused. Neurologic examination revealed disorientation to time, memory disturbances, decreased amount of speech, dysarthria, limitation of extraocular movement, ataxia of left limbs, and unsteady gait. He was treated with thiamine under the impression of Wernick's encephalopathy. Ataxia of limbs and unsteady gait improved but limitation of extraocular movement and disturbed higher cortical function remained. MRI of the brain taken 24 hours after the onset showed asymmetrical bilateral paramedian thalamic high signal lesions on 72-weighted images. We report here a case of bilateral paramedian thalamic infarction clinically mimicking Wernicke's encephalopathy.