Background: Sick neonates suffer from variable degree of renal impairment and AKI is a frequent phenomenon in NICU. The cause of AKI is of multi-factorial etiology and usually, there are one or more associated contributing factors. Early recognition of renal failure is important to facilitate appropriate fluid and electrolyte management & a stable biochemical milieu to prevent permanent renal damage. Methodology: We conducted a prospective observational study at NICU of our tertiary care hospital, Nalanda Medical College & Hospital, Patna over 15 months from March 2019 to May 2020. Sick babies of gestational age ≥26 weeks and birth weight ≥800 gram admitted in NICU were included in the study & their kidney function was monitored. AKI was defined as per serum creatinine &/or urine output criteria. Results: 459 neonates were studied out of which 57 (12.4%) suffered from AKI. Mean gestational age of neonates with AKI was 33.4 (S. D=4.4) and mean weight on admission was 2.172 Kg (S. D= 0.840 kg). Male: female ratio was 1.48:1. Out of theses neonates with AKI, a diagnosis AKI was made by 24 hours of admission in 34(59.6%) and in the rest 23 (40.4%) neonates, it occurred after 24 hours of admission. The most common type of AKI was pre-renal type which accounted for 73.7% (n=42) of cases. Intrinsic renal and post-renal causes accounted for 19.3% (n=11) and 7.02% (n=4) cases respectively. The common predisposing factors were sepsis (61.4%), asphyxia (49.1%), shock (54.4%) and dehydration (12.3%). Oliguric renal failure was seen in 25 (43.9%) cases and the underlying etiology did not play a role in the occurrence of oliguria. Out of the 57 neonates with AKI, 21 (36.9%) died. No difference in mortality was observed on the basis of sex, prematurity, SGA, birth asphyxia, dehydration, hyponatremia, hyperkalemia or metabolic acidosis. However, in this study we found a significantly higher mortality in the presence of sepsis, oliguria, higher mean serum creatinine level, and need of mechanical ventilation. Conclusion: AKI is a common phenomenon complicating the management of sick neonates with almost 1 in every 8 neonates admitted to our NICU suffering from this condition. As pre-renal AKI was the commonest type, this underscores that prompt recognition and management of hypoperfusion can prevent progression from pre-renal to intrinsic renal type of AKI. Most of such unfortunate neonates had more than 1 predisposing factors & sepsis and perinatal asphyxia were the most common risk factors for AKI. As non-oliguric AKI was more common than oliguric AKI, there was a high probability of missing 3 out of 5 cases with AKI if the focus was only on the urine output of a sick neonate. The presence of sepsis, oliguria, higher mean serum creatinine level, and use of mechanical ventilation were more commonly associated with mortality in such neonates.