Congenital hyperinsulinism (CHI) is one of the main causes underlying the development of persistent hypoglycemic conditions in children. Biochemically, CHI is characterized by inadequate insulin secretion from pancreatic β-cells. CHI is a heterogeneous pathology in terms of clinical manifestations, morphological features, and molecular-genetic defects contributing to its development. The present paper is focused on the current views of CHI pathogenesis; the clinical characteristic of the disease is given and the internationally accepted protocols for the examination and treatment of children with congenital hyperinsulinism are described.