The actuality of the present work is backed by the last 100 years of studying of the child urinary tract infections (UTIs). At the beginning of the 20th century Walter Birk, a famous German pediatrician, established the fact that these diseases proceed differently in infants and children, that girls get infected 10 times more often that boys, E. coli being dominant in the etiology. Walter Birk pointed out that anatomical organization of female urino-genital organs was not the principal reason for higher disease rates among girls. However, that time this point of view was neither proved, nor disproved convincingly. Another Walter Birk’s postulate which says that chronic suppuration may be cured with the help of natural health-improving factors also was not developed; the antibiotic therapy still being the dominant way of treatment. Clinical and experimental research work which we carried out has shown that many of the theses advanced at the beginning of the 20th century are still up-to-date, however, a number of considerable changes in etiology took place; the number of boys infected with UTIs grew considerably, which already makes it a tendency. The experimental research work has shown the role of the universal mechanism of the process of urinary tract infection.