Background. Blood lactate level is often considered as a marker of complex metabolic disorders. Reducing the lactate’s level is a good indicator of therapy adequacy. The purpose: to show the significance of the determination of lactate for predicting the course of the postoperative period in newborns. Materials and methods. 77 infants with abdominal surgical pathology were included in an observational study. Lactate level was measured on admission to the intensive care unit and three times in the first seven days of the postoperative period. Results. ROC-analysis model showed a high predictive value of the indicator at the end of the first postoperative day and on the seventh day. Favorable outсome was connected with lactate ratio below 2.5 mmmol/L on admission, lower than 2.0 mmol/l in the third and seventh days. Point elevation to 3 mmol/l was marked at the end of the first postoperative day. Conclusion. It is advisable to manage a dynamic assessment of lactatemia at the end of the first day and to the end of the third day of the postoperative period.