A 75-year-old woman with hyperinsulinemic hypoglycemia who died of acute myocardial infarction with ventricular rupture is reported. The microscopic examination of the pancreas revealed that the cause of hyperinsulinemic hypoglycemia was nesidioblastosis characterized by the presence of enlarged, irregular islets of Langerhans and clusters of islet cells in close proximity to the ducts. To our knowledge, nesidioblastosis in adults has not been previously reported in Israel.