Pyrimidines are widely used in agriculture as compounds included in fungicidal preparations with a wide spectrum of action. A systematic study of the biological activity of pyrimidine derivatives has shown that compounds of this class have a wide range of pesticidal properties. Among them, various plant growth regulators, herbicides, insecticides and acaricides, fungicides and bactericides, herbicide antidotes, etc. were found. In addition, pyrimidine derivatives are intermediates for the production of many active organo-phosphorus insecticides, urea and carbamic acid derivatives. Among other things, an important section in plant protection is of no small importance – phyto-sanitary, this is the application in practice of evidence-based measures aimed at protecting against risks arising from the penetration, fixation or spread of organisms harmful to plants and plant products, and for the improvement environment. The use of pyrimidines as chemical plant protection agents stimulated the development of a wide range of synthetic methods for their preparation and their chemical transformations, as well as the study of new properties of substances known and non-toxic to humans, which include some derivatives of dihydropyrimidines such as monastrol, oxymonastrol. Monastrol is now actively used in the treatment and prevention of infections caused by protozoan parasites belonging to the genus Leishmaniasis.