The purpose of the work: to reveal the laws of the influence of the ionizing radiation and glucocorticoids on the catalytic properties of the 5('-nucleotidase of the plasmatic membranes, to clear up the role of the sulphhydrilic groups in the modification of the 5('-nucleotidase. The laws of the radiation vulnerability of the plasmatic membranes have been established by the activity tests and kinetic parameters of the 5('-nucleotidase, as well as its reaction on the glucocorticoids and thiol agents. The obtained results have been included in the curriculum process of the biologo-soil faculty of the Tomsk State UniversityAvailable from VNTIC / VNTIC - Scientific & Technical Information Centre of RussiaSIGLERURussian Federatio