The study aimed at determining the prevalence of Chlamydia pneumoniae infections in children with asthma and healthy children aged 7-15 years, and defining the association between asthma severity and asthma exacerbation episodes in children with such infections. The group included 120 children. Immune responses against Ch.pneumoniae infections (IgM, IgA and IgG class antibodies) were studied using the microimmunofluorescence method (MIF). Serology results showed that acute and chronic Ch. pneumoniae infections were significantly more common in asthmatic children as compared to healthy subjects and they constituted a significant factor in this chronic disease exacerbation. The number of asthmatic children with positive serology after 3 and 6 weeks following an exacerbation episode was significantly higher in the experimental vs. control patients (90%, 92% vs. 62%; p=0,00 I); similarly, after a 24-hour follow-up, children with asthma included a significantly higher number of patients with positive serology as compared to the controls (95% vs. 87% vs. 74%; p=0,02). Prolonged presence of serological indicators of acute Ch. pneumoniae infections was seen in acute and chronic asthma patients and in children with recurrent exacerbation episodes. Children with asthma and respiratory tract Ch. pneumoniae infections showed a significantly higher eosinophil count in peripheral blood.