Premature babies in early postnatal ontogenesis are characterized by the immaturity of many functional systems, including the digestive system. The imperfection of the motor-evacuation function of the gastrointestinal tract in them is combined with insufficient activity of the enzyme systems, the peculiarities of the formation of the microbial landscape of the colon, which contributes to the development of digestive dysfunctions and complicates enteral feeding, especially in deeply premature infants. In order to determine the parameters pancreatic elastase (PE) in premature infants, depending on the gestational age and the nature of feeding, 135 newborns were examined (108 premature infants with a gestational age of 22 to 32 weeks and 27 term infants). All children underwent a general clinical examination, as well as a study for PE on the 13–14th day of life, when the volume of enteral nutrition reached 70 percent or more. Analysis of the study results revealed a clear relationship between the degree of prematurity and the severity of pancreatic insufficiency. A clear relationship between fecal elastase indicators and the type of feeding was determined. The most favorable situation is observed in exclusively breastfed children, who have the highest fecal elastase values, which practically do not differ from the control values. The research was carried out in accordance with the principles of the Helsinki Declaration. The study protocol was approved by the Local Ethics Committee of these Institutes. The informed consent of the patient was obtained for conducting the studies. No conflict of interest was declared by the authors. Key words: premature, elastase, pancreatic insufficiency.