AIM: To evaluate urinary Neutrophil Gelatinase-Associated Lipocalin (uNGAL) as a predictive biomarker for Acute Kidney Injury (AKI) in neonates undergoing gastrointestinal surgery. MATERIALS & METHODS: A prospective cohort study included 45 neonates with gastrointestinal congenital malformations who underwent abdominal surgery within the first 28 days of life at two pediatric centers in Almaty, Kazakhstan. AKI was diagnosed using modified neonatal KDIGO criteria, dividing neonates into AKI[+] and AKI[-] groups. uNGAL levels were measured pre-surgery and on postoperative days 1, 3, and 7. Statistical analysis, including ROC curve analysis, was performed using SPSS to evaluate uNGAL's sensitivity and specificity as a biomarker. RESULTS: AKI was diagnosed in 42.2% of neonates. Pre-surgery uNGAL levels were significantly higher in the AKI group (184.4 ng/ml vs. 56.5 ng/ml). Post-surgery, uNGAL peaked at 493.9 ng/ml on day 1, with sensitivities of 89.5% and 94.7% on days 1 and 7. Specificity was highest on days 1 and 3 (96.2% and 100%). The mortality rate among AKI-affected neonates was 31.5%. CONCLUSION: uNGAL is a sensitive and specific biomarker for early AKI detection in neonates post-gastrointestinal surgery, enabling timely interventions and potentially reducing mortality.