Wernicke's encephalopathy may result in severe morbidity and possible mortality when unrecognized. We report a distinctive acid-base pattern that has not been associated with this syndrome. This is a case series of patients with Wernicke's encephalopathy who had an arterial blood gas measurement performed on initial presentation. Exclusion criteria were patients with an unclear diagnosis of Wernicke's encephalopathy and those for whom no arterial blood gas measurement was performed. Four patients with Wernicke's encephalopathy were included in the analysis. All 4 patients exhibited an anion-gap (primary) metabolic acidosis, accompanied by a primary respiratory alkalosis. Three of 4 patients exhibited a significant lactic acidosis. None of the patients had any competing diagnoses or dysfunction to account for this acid-base pattern. Patients with Wernicke's encephalopathy may exhibit a distinctive acid-base pattern consisting of a primary metabolic acidosis in conjunction with a primary respiratory alkalosis. Observation of this acid-base disturbance should prompt clinicians to consider thiamine deficiency disorders as a possible cause.