History and admission findings | A 41year old woman presented at our internistic clinic after treatment by an emergency doctor because of confusion and amnesia accompanied by a hypoglycaemic episode while driving her car. Only by giving continuous glucose intravenously a stable clinical state could be achieved. In her medical history she took Lamotrigin for 12 years since she had seizures of unknown aetiology. 16 years ago she had similar sudden attacks with confusion and hypoglycaemia. At that time thorough diagnostics at the clinic for internal medicine did not reveal any evidence for hyperinsulinaemia. While taking Lamotrigin the patient had no seizures or similar symptoms for 12 years. Treatment and course | In the present case we detected a tumor in the pancreas and a two-fold increased insulin secretion. Histopathological work-up of the removed tissue confirmed the suspected diagnosis of insulinoma. Postoperatively, Lamotrigin treatment was terminated. Since then the patient remained asymptomatic.