Nowadays it is common to observe the growth of viral-viral and viral-bacterial co-infections in children of different ages, due to dysfunction of lymphocytes (DL), which can be connected with the process of the accelerated shortening of the end structures of chromosomal telomeres, telomere length changes are described in lymphocytes of children with chronic mono-infections. The conducted study has shown the shortening of telomere lymphocytes in children with CDRT seropositive for mixed-herpes viral infections (herpes simplex virus, virus, Epstein-Barr virus and cytomegalovirus in various combinations) and for bacterial co-infections - Chlamydia trachomatis and (or) Mycoplasma pneumoniae. The use of regression analysis and attribute analysis (in percent) made possible to neutralize age-groups differences of seropositive and seronegative children. Thus showed that children, who suffer from chronic diseases of the respiratory tract associated with mixed-herpes viral and bacterial co-infections, have more pronounced telomere shortening of lymphocytes than seronegative children of the same age.