In the largest series of patients with glibenclamide-associated hypoglycaemia reported so far, 51 cases reported to the Swedish Adverse Drug Reactions Advisory Committee and six additional cases are reviewed and related to sales and prescription data of glibenclamide. Median age of the patients with hypoglycaemia was 75 years and 21% were 85 years or above. For comparison, the median age of a random sample (1 in 288 of all patients prescribed glibenclamide) was 70 years and only 5% were 85 years or older. In eight out of 40 cases where duration of glibenclamide treatment was recorded, the hypoglycaemic event occurred during the first month of treatment. The median daily dose of glibenclamide prescribed was 10 mg both in the hypoglycaemic cases and in the prescription sample. Coma or disturbed consciousness was the most common clinical presentation in this series and the minimum blood glucose value was 1.3 mmol/l (median). Twenty-two patients responded immediately to treatment, 24 had protracted hypoglycaemia of 12-72 h duration and 10 died. Fatal outcome was observed even with small doses of glibenclamide (2.5-5 mg/day). Previous strokes and cardiac disorders were isolated as two independent determinants of a serious course of the hypoglycaemia. Other contributing factors included impaired renal function, low food intake, diarrhoea, alcohol intake and interaction with other drugs. Thus, it is not uncommon for glibenclamide, like the first-generation sulphonylureas, to cause serious, protracted and even fatal hypoglycaemic events.