Glucocorticoids are anti-inflammatory and immunosuppressive agents which have pleiotropic effects on growth, differentiation and functional activity of T-lymphocytes. Under experimental conditions in vitro carried out a comprehensive assessment of the dexamethasone influence on the functional activity of T-cells with different differentiation degrees. It was established that the influence of dexamethasone on the functional activity of CD45RA+ and CD45RO+ T-lymphocytes, in general, has depressing character. It was revealed that in the population of naive (CD45RA+) T-cells dexamethasone exerts a more pronounced inhibitory effect on early (IL-2-dependent, associated with the CD25 expression and IL-2 production) activation stages, whereas in the culture primed memory cells (CD45RO+)--for later (IL-2-independent, associated with the expression of proliferation molecule CD71). Multidirectional effects of dexamethasone on the expression level of telomerase catalytic unit (hTERT) mRNA are associated with the degree of T cells differentiation. It isproposed, that the role of glucocorticoid hormones in immunogenesis is primarily aimed at suppression of excessive T cells growth and on the maintainance of the clonal balance in lymphoid tissue.