Abstract
Assuming as a starting point the immunological system tasks in the human organism it was shown that an increasing impairment of this system functioning with age is due to a cumulative effect of many factors, and particularly of physiological involution of the thymus, progressing with age and resulting in a decreased cellular and humoral immunity; changes in biochemical and genetic factors underlying immunological phenomena, and accumulated detrimental effects of human habitat. The net result of these disadvantageous changes in older people most often consists in: (l) a low ability to extinguish infections; (2) inability to efficiently resist neoplasms; (3) a tendency to autoimmunization. Regular patterns of change in the immunological system of the aging man suggest a number of elementary immunopreventive and immunotherapeutic measures to be applied by physicians of the first contact with elderly and aged patients.