BACKGROUND: Acute kidney injury is a severe clinical condition. It is common in neonates in intensive care unit. It is defined as a sudden deterioration in kidney function resulting in derangements in fluid balance, electrolytes, and waste products. The score for neonatal acute physiology perinatal extension in critically sick neonates with kidney injury is a useful tool for assessing the severity of the disease. AIM: This study aimed to determine the incidence of AKI and the role of SNAPPE 2 score in predicting mortality and morbidity of kidney injury in neonates. METHODS: The study was designed as a prospective clinical investigation performed in the period of three years, which included 100 neonates (50 with AKI and 50 without AKI) hospitalised in intensive care unit of University Clinic of Children Diseases in Skopje. The severity of the illness of hospitalised newborn infants was estimated with SNAPPE 2 score realised in the first 12 hours of admission to NICU. Medical data records of admitted neonates with AKI were analysed. The material was statistically processed using methods of descriptive statistics. RESULTS: During the study period, 770 new born's were hospitalised in the intensive care unit due to various pathological conditions and 50 new born's were selected with AKI. The control group consisted of 50 neonates with comparable associated pathological conditions, but without kidney injury. The calculated prevalence of AKI in neonates was 6.4%. Most of the involved neonates in the study in both groups (AKI and non-AKI) were born at term (64% and 54%) with a predominance of male neonates (68% and 60%). The mortality rate was significantly higher in newborns with AKI than in the control group (36% vs 24%) (p < 0.01). The mean SNAPPE 2 score value in neonates with AKI was higher than in the control group (58.72 vs 40.0), and the difference was significant (p = 0.00001). Difficult score level predominated in half (50%) of newborn infants with AKI, while median score level predominated in control group (42%). There was a significant difference between the mean score value in neonates with AKI and lethal outcome compared to neonates with AKI without lethal outcome (70.73 ± 18.6 vs 40.2 ± 16.6) (p < 0.0001). CONCLUSION: Acute kidney injury is a life-threatening condition with still high mortality rate. The severity of the illness of hospitalised neonates in an intensive care unit is estimated by SNAPPE 2 score. Also, the risk of mortality is estimated too, taking into consideration the fact that higher values of the score are associated with higher mortality. Appropriate treatment of neonates with severe kidney injury improves the outcome and reduces the mortality of the disease.