Background. Newborns often develop purulent septic complications soon after surgical treatment of inherent gastrointestinal pathology. The aim: to define the prognosis significance of catelicidine (LL-37) as the marker of inflammatory complications during the post-operation period in neonates with gastrointestinal pathologies. Patients and methods. 21 newborns with inherent intestinal obstruction were included into the study. Each child received surgical correction of the defect. The children were divided into 2 groups: group 1 (n = 10) — newborns with purulent inflammatory complications after the operation (anastomosis failure — 2, peritonitis with ileus — 3, sepsis and pneumonia — 5); group 2 (n = 11) — children with no post-surgery complications. Healthy newborns formed the reference group (n = 20). The level of catelicidine LL-37 in the blood plasma was determined in all the children at delivery (BCM Diagnostics). Patients in groups 1 and 2 had their catelicidine LL-37 concentration measured on the 1,3,7 and 14th day after surgery.Results. A statistically significant (p < 0,05) difference in catelicidine was revealed only on the first day. While investigating the difference in LL-37 levels in the blood serum between children from the reference group and children from groups 1 and 2, statistically significant differences were found on all days. Conclusion. Determining the catelicidine level is an effective way of predicting post-surgery complications in the correction of developmental gastrointestinal defects.