Nineteen children underwent subtotal pancreatectomy for hyperinsulinemic hypoglycemia. Of the four who were older than 10 years of age at onset of symptoms, three had islet adenomas, and one had endocrine cell dysplasia (ECD). The two patients with multiple adenomas had a family history of multiple endocrine neoplasia, type 1 (MEN 1). Of the 15 who were younger than 1 year of age at onset of symptoms, 12 had ECD alone, and three had ECD with adenomatosis. Four children required a second surgical procedure and near-total pancreatectomy because of persistent hypoglycemia. All 19 patients' conditions improved, with no postsurgical complications. After near-total pancreatectomy, all four patients were treated for fat malabsorption, but only two required insulin because of secondary diabetes mellitus. We concluded that subtotal pancreatectomy is a safe, effective adjunct to the treatment of children with hyperinsulinemic hypoglycemia.