The article is devoted to one of the hereditary disea­ses — mucopolysaccharidosis type II, which is caused by deficiency of lysosomal enzymes, which leads to the catabolism disorder of the basic substance of the connective tissue mucopolysaccharide molecules — carbohydrate portion (glycosaminoglycans). The tissues (mainly the fibroblasts and mesenchymal cells) accumulate chondroitin sulphate and/or geparanmonosulfat that leads to defective structure of connective tissue, causing gross cellular changes and the development of typical clinical picture. The peculiarities of their clinical manifestations involve manifold of clinical signs, involvement of many organs and systems in the pathological process, different age of onset of the disease that complicate the diagnosis of these diseases. If there is any marked clinical polymorphism (infantile, juvenile, adult forms) all lysosomal diseases are characterized by progressive course, and most of them lead to early disability and premature death. The mucopolysaccharidosis II type as Hunter syndrome is widely spread in the world. The authors present their own clinical observation and indicate the characteristics of the course of respiratory disease in this group of adult patients.