The aim of our study was to determine the possible pathophysiological mechanisms of hypophosphataemia in a group of 127 patients admitted to hospital for alcohol-related causes. Blood and fresh urine specimens were taken to determine acid-base and electrolyte parameters. Thirty-seven patients (29.1%) had hypophosphataemia (serum phosphorus 20%, TmPO4/GFR < 0.80 mmol/l) was evident, possibly due to hypomagnesaemia, metabolic acidosis, metabolic alkalosis, or a proximal tubular defect in phosphate transport. The causes of hypophosphataemia in the remaining 20 patients were alcohol withdrawal syndrome, respiratory alkalosis and diarrhoea. Patients with hypophosphataemia were more often found to have hypomagnesaemia and respiratory alkalosis than normophosphataemia patients. In conclusion, hypophosphataemia is frequently observed in alcoholic patients due to various pathophysiological mechanisms, such as inappropriate phosphaturia, increased phosphorus entry into cells and increased gastrointestinal loss of phosphate.