An attempt is made in this paper to draw up some results of long-term studies conducted by the "Immunoprophylaxis" Center of RANS on such studies. The results of mass and individual studies among 250 thousand blue- and white-collar workers in Russian industrial enterprises are processed in the data bank of the Center, including an analysis of the immunological reactions of 30 thousand individuals studied. An analysis of the results shows that secondary immunodeficiency is encountered in 30% of the people occupied in industrial positions, in 40% of professional athletes and in more than 60% of the children studied. It should be emphasized that in enterprises where there is substantial excessive environmental harm, the frequency of development of immunodeficiency also exceeded the 60% mark. There are many reasons for the development of immunological deficiency and they depend on a large number of factors. Among them, in the first place, is the anthropogenic effect on the environment, which results in contamination of working zones, the earth, water and, as a consequence, food products, the use of which inevitably results in immunodepression. A special place in this problem is occupied by stress, which accompanies almost any professional activity. There is no doubt concerning the opinion that normal functioning of the immune system provides a sufficiently effective "interdiction" against the development of many diseases. Immune deficiency "opens the door" to illness. In other words, immunodeficiency is a detonator for the growth of a pathology.