The authors experienced an anesthesia for surgical removal of insulinoma of pancreas in 66 year old woman. The patient showed symptoms of Whipples triad (hypoglycemia, low circulating glucose level and prompt relief of symptoms after glucose administration). On the abdominal CT scanning, round distal pancreatic tumor mass was detected. The patient was premedicated with Robinul 0.2 mg, diazepam 10 mg. On arrival in operating theater, the patients blood glucose level was 38 mg/dl (measured with Glucometer), despite of the low blood glucose level, she was free without any apparent symptoms. But we infused 50% D/W 50 ml rapidly and subsequently dropped 5%D/W solution and the blood gucose level was increased to 162 mg/dl before induction of anesthesia. Anesthesia was induced with thiopental sodium 250 mg IV, followed by succinylcholine 50 mg IV for endotracheal intubation and maintained with enflurane-N2O-O2, pancuronium 4 mg was administered intravenously for muslce relaxant. The blood glucose level was measured with Glucometer every 15 minute. No hypoglycemic episode was observed during anesthesia.