Authors present 19 children aged from 2 weeks to 16 y with severe hypoglycemia. In 3 oldest children a single nesidioma was found. In other 16 children mainly infants nesidioblastosis has been recognised, and in those cases the subtotal pancreatectomy was performed. In 4 infants the additional resection of the pancreas was done because after the primary procedure hypoglycemia persisted. All patients survived and were euglycemic. Severe hypoglycemia leads to brain damage and therefore should be treated as an urgent state.