Aim. To present data on the structure of bacterial pathogens causing infectionsin cancer patients atthe N.N. Blokhin National Research Center of Oncology and analyze them in comparison with data of domestic and foreign literary sources.Materials and methods. The data of 11,853 microorganisms isolated from patients hospitalized in the N.N. Blokhin National Research Center of Oncology in 2023 were analyzed.Results. Bacteria accounted for 90.0 % of all isolated microorganisms and only 10.0 % were fungal pathogens. Despite the fact that gram-negative pathogens have given way to gram-positive pathogens in absolute numbers, gram-negative microorganisms (60.7 %) still prevail in “clinically significant” biomaterials (blood, spinal fluid, urine, wound discharge, BAL, etc.), primarily Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Acinetobacter baumannii and others. With the exception of Escherichia coli, a high percentage of carbapenem-resistant strains is noted for other pathogens: Klebsiella pneumoniae – 34 %, Pseudomonas aeruginosa – 50 %, Acinetobacter baumannii – 69 %. Real-time polymerase chain reaction revealed the leading carbapenemases: in Klebsiella pneumoniae strains – KPC or OXA-48 carbapenemases were detected in 55 % of cases, and NDM metallo-β-lactamasesin 45 %; in Pseudomonas aeruginosa strains – VIM metalloβ-lactamases were registered in 29 % of cases. Among gram-positive microorganisms, the most problematic is vancomycinresistant Enterococcus faecium. It accounts for 45 % of all E. faecium strains.Conclusion. Along with modern diagnostics and infection control measures, knowledge of the leading microbiota in a particular clinic will prevent the spread of infection and provide timely medical care to patients.