Beer drinker's hyponatraemia, also called beer potomania, is a syndrome of hyponatraemia in patients who consume excessive amounts of beer and have a poor dietary intake. We describe a patient with chronic asymptomatic hyponatraemia due to beer potomania. The pathophysiology of this syndrome, the treatment and prevention are reviewed. (See Expert opinion p, 101,) (C) 1999 Elsevier Science B.V. All rights reserved.