Background: Protein-energy malnutrition is rather common desease for toddlers nowadays. The statistics show that level of mortality among toddlers with protein-energy malnutrition is increasing. Сhanges of protein metabolism under protein-energy malnutrition have gradual and adaptive nature. Material and methods: We have examined 100 children with protein-energy malnutrition. Children’s age ranged from 1 to 12 months of life. Quantitative determination of α-1-antitrypsin was performed using immunoturbidimetric method. The folloving groups are specified: Group I (the main group n = 50) – toddlers with protein-energy malnutrition (PEM) with perinatal affection of the central nervous system (PA CNS). Group II (the comparison group n = 50) – toddlers with (PEM) without (PA CNS). The control group comprised practically healthy toddlers, whose physical development corresponded to their age. Results: The results of the study of protein metabolism of toddlers with protein-energy malnutrition showed an increase of α-1-antitrypsin as compared with the control group and the comparison group (p < 0.05). In toddlers with PEM and PA CNS metabolism disorders are manifested by the increase of 2-1-antitrypsin content in the blood serum unlike the index of control and comparison groups (р < 0.05). 2-1-antitrypsin, as the index of protein metabolism, had a high sensitization 82.5% and specificity 87.4% in toddlers with PEM, while the sensitization of common protein level made up 79.4% and its specificity only 41.3%. Conclusions: Increased level of α-1-antitrypsin in the serum of blood of toddlers with protein-energy malnutrition indicates the predominance of catabolic processes. The determination of α-1-antitrypsin level in blood serum of toddlers with PEM, probably, may reflect not only protein metabolism disorder and protein-synthetic function of liver, but also the predominance of catabolic processes even at the early stages of this disease development.