This article presents modern data on epidemiology, etiology, and clinical manifestations of mucopolysaccharidosis (MPS) type I in children. MPS develops due to deficiency of particular lysosomal enzyme which determines the disease type. The article considers in details disease’s pathogenesis and classification. Evidence-based approaches to diagnosis (differential diagnosis included) are covered, moreover, special attention is paid to pathogenetic, symptomatic, and surgical treatment of MPS.