3-nitrotyrosine (3NTYR) produced by the reaction of nitrogen and oxygen species is used as a suitable marker of radical mediated tissue damage. Free or protein-bound tyrosin residues are in vivo nitrated most likely by peroxynitrite or myeloperoxidase. Processes involved in formation and degradation of 3NTYR are not completely clear. It seems that degradation depends on the way in which 3NTYR is formed, characteristics of the tissue or organ where 3NTYR was formed and even general condition of the organism. Nitration of tyrosine does not only modify the biochemical structure of the protein but usually affects its function. Nitrated proteins are probably specific for each organ and may influence the pathogenesis of the disease. The review also describes the methods of 3NTYR detection and summarizes published data on 3NTYR concentration in various human diseases.

        Key words: 3-nitrotyrosine, peroxynitrite, reactive nitrogen species, reactive oxygen species