There is a limited number of publications on the incidence of different mutations in the BCR-ABL kinase domain, the efficacy and safety of therapy in children and adolescents with resistant forms of chronic myeloid leukemia (СML). Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is still the only method able to cure the disease completely in pediatric and adolescent patients with CML, however, being associated with life-threatening complications. This article analyzes the course, treatment and outcomes of chronic myeloid leukemia in 3 pediatric patients pre-treated with tyrosine kinase inhibitors (TKI) who exhibited the T315I mutation in BCR-ABL kinase domain.