Introduction. It was found that the body's response to various stressful effects is largely determined by the ratio of the tone of the sympathetic and parasympathetic parts of the autonomic nervous system. It was revealed that in those days when a predominance of the parasympathetic nervous system tone was noted stressful effects caused more significant and negative changes in the body. The autonomic nervous system is also influenced by climatic factors. Materials and methods. 5305 males of different age were examined with the help of functional vegetative diagnostics according to the method of V. Makats. The bioelectric activity of 12 symmetric pairs of functionally active zones of the skin (24 FAZ), 12 on the hands and 12 on the feet, which reflect the functional activity of the sympathetic and parasympathetic nervous systems were studied. Results. In the study of systemic age dependence in all male observation groups the change of seasons of the year has been found to lead to changes in functional activity and homeostasis of the organism. The seasonal indicators of the activity of functional systems (FS) are clearly observed to duplicate the norm line, differing in amplitude and having the same orientation. Moreover, the presence of significant changes in the studied parameters of activity indicators of FS with the norm line indicates that all seasons of the year were characterized by differences. Conclusions. It has been established that the season change on the body leads to significant changes in functional activity and homeostasis of men of different age groups. The dependence of these indicators indicates a species evolutionary adaptation of a human to seasonal changes in climatic conditions.