Among the many complexes of organic and inorganic compounds of tin which have been applied in practice, tri-substituted organic compounds of tin such as tributylocine (TBT) are crucial in chemistry and environmental toxicology. All trisubstituted compounds of tin are strong biocides. They are used in protecting wooden construction and textiles against fungi and in fighting organisms that grow on underwater structures. The author emphasizes that the use of anti-lichen paints containing tributylocine may result in very hazardous environmental pollution.