Wernicke's encephalopathy, a disorder with significant mortality and high morbidity, is common amongst alcohol-dependent patients. Thiamine deficiency appears to play a key role in its aetiology, and parenteral high-dose thiamine is effective in prophylaxis and treatment. Unfortunately, reports of rare anaphylactoid reactions have led to a dramatic reduction in the use of parenteral thiamine, and it is possible that this change in treatment has led, or will lead, to an increase in morbidity and mortality. There is a need for education of doctors who treat alcohol-dependent patients, in order to ensure appropriate use of parenteral thiamine in prophylaxis and treatment of this disorder.