A comprehensive evaluation of biological indices has been carried out in 26 patients with depressive disorders and in 20 age- and sex-matched controls. Indices of programmed cell death (apoptosis) in subpopulations of blood lymphocytes and concentration of cortisone in blood serum were determined. Significantly enhanced apoptosis was observed in the lymphocytes of depressive patients as shown by increased percentage of lymphocytes expressing FAS-receptor and cells with morphological changes characteristic of apoptosis (nuclear condensation, vacuolation. Clinical symptoms of depression were concomitant with alterations of cellular link of immunity expressing in the decrease of the total T-lymphocytes (CD3+) number, T-helpers (CD4+) and natural killers (CD16+) as compared to healthy persons. The level of blood serum cortisone was increased in patients with depression. High cortisone values correlated with suppression of cellular CD4+ population and an increase of FAS-receptors expression in patients with depression.