Microbiological, immunological and immunohistochemical studies were carried out in 78 children with different clinicomorphological forms of chronic glomerulonephritis (GN). According to the data obtained, the role of streptococcal intection (SI) is inconclusive in certain clinicomorphological forms of chronic GN, suggesting different approaches to the treatment of these patients. The etiological role of SI is most probable in mesangioproliferative and mesangiocapillary GN, manifesting by hematuric and mixed forms of chronic GN. Antibacterial therapy is indicated to patients with a rise of the level of ASL-O and with the clinical signs of acute SI or exacerbation of chronic tonsillitis in the same patients, especially during immunosuppressive therapy.