A 67-year-old female with insulin-dependent diabetes mellitus underwent an uncomplicated partial liver resection under combined epidural and general anaesthesia. After surgery, 50 U of insulin were accidentally infused into her epidural space over a period of 5 h in addition to her prescribed intravenous insulin infusion. After recognition of the accidental epidural administration, the patient was closely monitored for any neurological signs or symptoms. Blood glucose levels decreased significantly from 17.4 to 6.8 mmol.l(-1) over a period of 7 h. Despite the hazard of potentially neurotoxic preservatives in the insulin preparation, she suffered no neurological sequelae and made an uncomplicated recovery.