Objective of the research: to evaluate the diagnostic and prognostic significance of determining NT-proBNP in blood plasma in newborns with congenital heart defects (CHD). Materials and methods: in the Department of Pathology of Newborns and Premature Infants, Department of Newborns, National Medical Research Center for Obstetrics, Gynecology and Perinatology named after V.I. Kulakov, the study of NT-proBNP level in the blood serum of full-term newborns was performed. The study included 133 children who were divided into 3 groups: group 1 (control group, n=41): healthy full-term children without any pathology in the neonatal period. In children of this group, NT-proBNP concentration was determined on the 1st and 7th day of life (d.o.l.), the results were used as NT-proBNP reference values. Group 2: newborns with non-critical CHD without signs of heart failure (HF) (n=24). NT-proBNP was determined in this group at 4–7th d.o.l. (upon admission to the Department of Pathology of Newborns and Premature Infants. Group 3 included newborn children with CHD and HF syndrome of degree 1 or 2A (n=68). NT-proBNP concentration was assessed upon admission at 1–3th d.o.l. (n=24), 4–7th d.o.l. (n=31) and 8–14th d.o.l. (n=17). In 27 children of group 3, the peptide concentration was monitored during ongoing therapy. 9 newborns who needed surgical correction of the defect from group 3 were assigned to subgroup 3A. Blood plasma analysis was performed by electrochemiluminescence on a cobas e411 immunochemical analyzer (Hitachi, Japan). Results: in group 1, on the first day of life, the highest NT-proBNP concentrations were observed (med = 4971 pg/ml, 10‰ – 260 pg/ml, 90‰ – 13 224 pg/ml), which decreased during the first week of life in almost 2,5 times (med = 2087 pg/ml, 10‰ – 331 pg/ml, 90‰ – 4478 pg/ml). In group 2 at the 4–7th d.o.l. the mean value of NT-proBNP was 3306 pg/ml (10‰ – 1506 pg/ml, 90‰ – 5765 pg/ml), which is slightly higher than in children of the reference group. In group 3, the highest concentrations of NT-proBNP were noted: in children with early developed circulatory failure: in 1–3th d.o.l. NT-proBNP amounted to 17 214 pg/ml (10‰ – 4258 pg/ml, 90‰ – 30 363 pg/ml), in 4–7th d.o.l. the mean value was 5077 pg/ml (10‰ – 1535 pg/ml, 90‰ – 25 542 pg/ml). These values exceed the reference more than 3 times. In group 3A, there was a significant increase in the concentration of NT-proBNP compared with other children of group 3, as well as an excess of the control group indicators by more than 5 times (med = 24 093 pg/ml, 10‰ – 4235 pg/ml, 90‰ – 41 115 pg/ml). The analysis of dynamics in children receiving HF therapy revealed a decrease in the concentration of NT-proBNP in the case of compensation. When the condition worsened, an increase in the concentration of NT-proBNP was noted, respectively. Conclusion: in newborns, NT-proBNP concentration at birth has a maximum value, decreasing during the first week of life by almost 2 times. Measurement of NT-proBNP concentration can be used in newborns with CHD and HF risk in the neonatal period. The assessment of NT-proBNP concentration in newborns in dynamics can be an additional criterion in assessing the therapy effectiveness.