Objective. To study clinical, anamnestic and laboratory features and to determine risk factors for necrotizing enterocolitis (NEC) in premature infants. Patients and methods. A retrospective analysis of the medical records of 47 premature infants with very low and extremely low birth weight (VLBW/ELBW) and NEC was performed. Newborns were divided into an early-onset group (n = 22) and a lateonset group (n = 25). Groups were compared for perinatal status, clinical symptoms, laboratory findings, and clinical outcomes. As a control group, 50 children without NEC were selected. Risk factors for the development of NEC were determined using multivariate logistic regression analysis. Results. When comparing groups with early- and late-onset NEC, it was noted that in the group with early onset, the number of children with the Apgar score at 1 minute ≤3, stage 3 NEC, surgical treatment, intraventricular hemorrhage ≥ grade 3, apnea and fever or hypothermia was higher. Multivariate logistic regression analysis showed that impaired enteral nutrition tolerance, early sepsis, severe anemia, and hemodynamically significant patent ductus arteriosus were independent risk factors for earlyonset NEC in VLBW/ELBW preterm infants (p < 0.05). Conclusion. Neonates with enteral intolerance, early sepsis, severe anemia, or hemodynamically significant patent ductus arteriosus are at higher risk of developing NEC. Key words: necrotizing enterocolitis, early diagnosis, premature, newborns