Contrast medium was given intravenously to three nonalcoholic patients who underwent MRI or CT in the acute stage of Wernicke's encephalopathy. Lesions enhancement was not seen in one patient examined within 4 days of clinical onset, was mild in a another 3 days after clinical deterioration and marked in a patient examined 12 days after admission. Contrast enhancement of lesions was present in half of 12 cases of acute disease reported previously. There was a substantial overlap in the time interval between clinical onset and contrast-enhanced CT or MRI in the groups of enhancing and nonenhancing lesions. Since contrast enhancement may be absent in acute WE, proton-density and T2-weighted images are more useful for diagnosis of this reversible but potentially fatal condition.