Background. Acute tumor lysis syndrome (ATLS) complicates the treatment of highly aggressive leukemias and lymphomas in children and leads to death in 21.4 % of severe cases. ATLS is based on the death of tumor cells, so the volume of decay products exceeds the excretory capacity of the kidneys. The ATLS risk group includes patients with acute lymphoblastic leukemia accompanied by hyperleukocytosis (above 100 × 109/L) and non-Hodgkin’s lymphomas with a large tumor mass (stage III–Iv of the disease). The development of acute renal and then multiple organ failure require intensive monitoring of ATLS clinical and biochemical markers and the development of optimal patient management tactics jointly by an intensive care physician and a pediatric oncologist-hematologist.Aim. To summarize the literature and our own clinical experience in the diagnosis and treatment of ATLS in pediatric oncohematology.Materials and methods. The literature data on the diagnosis and treatment of ATLS in children with oncohematological diseases were analyzed. Summarized own clinical experience from January 2009 to January 2022.Results. Of 379 patients with acute lymphoblastic leukemia and non-Hodgkin’s lymphomas, who are at risk for developing ATLS, 350 (93.4 %) patients underwent conservative ATLS therapy, of which in 31 (8.8 %) cases, hemodiafiltration was required to eliminate tumor decay products. The average number of hemodiafiltration procedures is 3 (from 1 to 15). Nevertheless, despite the whole range of therapeutic measures, the addition of infectious and multiple organ complications caused death in 7 (22.6 %) of 31 patients. Most (5 out of 7) fatal cases occurred between 2009 and 2013, and the number of lethal cases because of ATLS from 2014 to 2022 years were only 2. In 24 (77.4 %) patients, the signs of ATLS were successfully managed, the patients continued antitumor treatment. when observing patients for 6 years (from 7 months to 13 years), there were no signs of disease relapse, as well as renal dysfunction.Conclusion. prevention and treatment of ATLS, including cytoreductive prephase, infusion therapy, allopurinol and rasburicase, and in case of ineffectiveness, hemodiafiltration is the basis of modern intensive therapy for hematological malignancies in children. Additional study of the pathogenetic mechanisms of ATLS development, identification of key targets of drug therapy, and a multidisciplinary approach in the treatment of an extremely unfavorable group of oncohematological patients with advanced stages of the tumor process are possible components for further increasing the effectiveness of ATLS therapy.