Hypokalaemia is commonly found among the electrolyte abnormalities observed in chronic alcoholics. However, the underlying mechanisms of the decreased potassium levels are not well known. We undertook the present study to analyse the possible pathogenetic mechanisms of hypokalaemia in a large group of alcoholic patients (n = 127) admitted to our hospital for causes related to alcohol abuse. Serum potassium levels were significantly lower in alcoholic patients compared to the control population (3.8 + 1.1 mmol/l vs. 4.6 + 0.9 mmol/l). In 12 of these patients inappropriate kaliuresis was observed due mainly to the coexistent hypomagnesaemia. Two of the remaining four patients had a history of diarrhoea, while the other two had alcohol withdrawal syndrome with considerable respiratory alkalosis. Patients with hypokalaemia had hypomagnesaemia and respiratory alkalosis more commonly compared to the normokalaemic ones. We conclude that hypokalaemia is a relatively common electrolyte abnormality observed in alcoholic patients owing to various pathophysiological mechanisms. Among them, inappropriate kaliuresis due to the co-existent hypomagnesaemia predominates.