Thirty-three patients were studied in the acute stage of severe brain injury, 18 patients died during 24 days in a hospital, 15 patients had survived. The functional status of autonomic, hypophysis-adrenal and immune systems was followed up using variation cardiointervalography, Adrenocorticotropic hormone (ACTH) and cortisol as well as cell immunity parameters were measured. In patients with a fatal outcome, the overstrain of compensatory mechanisms of autonomic supply (mode amplitude, AMo and index of strain, IS) noted in the first day was exhausted to 19-22 days. The hyperreactivity of the adrenocorticoid system was characteristic of all patients. The wavelike character of the changes in mean concentration of cortisol, along with the decrease in ACTH, was observed in patients with a fatal outcome while cortisol and ACTH gradually decreased in survived patients. In patients with a fatal outcome, the helper-induction activity was dramatically inhibited after the short-term elevation. These parameters were correlated with the dynamics of mortality: the first peak of mortality was at the first week, along with the overstrain of the autonomic-endocrine regulation; the second peak was at 21-26 days, it was associated with a sharp reduction of hormone production, "immunological pit" and an exhaustion of the adaptive-compensatory mechanisms of the autonomic nervous system.