The monograph presents the literature data and the results of its own study of interindividual differences in the immune responses of rats of both sexes to chronic restraint stress and their neuro-endocrine accompaniment. The individual nature of the immune system's response to chronic stress has been demonstrated, and three different variants of immune responses and its neuroendocrine support have been identified and detailed. For the first time, canonical correlations between the parameters of immunity (thymocytogram, splenocytogram, immunocytogram of blood, blasttranformation of lymphocytes, phagocytosis parameters of macrophages and microphages) and neuroendocrine regulation (sympathetic and vagal tone, plasma levels of corticosterone, testosterone, thyroxin, triiodothyronin as well as mineralocorticoid, calcitonin and parathyroid activities) have been identified. It has been shown that chronic stress is accompanied not only by pathological but also by compensatory changes in the parameters of the immune status. For the first time, sexual dimorphism of the immune status of rats was described in detail both normal and after weekly moderate chronic immobilization-aversion stress.