Some species of soil bacteria and most organisms living in extreme environments such as salt lakes or coal or salt mines have effective protective mechanisms that enable them to function under adverse conditions. A common way to protect against harmful environmental factors is the production and accumulation of substances with an osmoprotective effect. One of such substances is ectoine, or 1,4,5,6-tetrahydro-2-methyl-4- -pyrimidine-carboxylic acid of an amphoteric nature. The effect of ectoin, mainly based on the binding of water molecules, has found wide application in the protection of macromolecules and cells. This work is a review of the use of this amino acid in human and veterinary medicine.