Background: Acute kidney injury (AKI), formerly called acute renal failure (ARF), is commonly defined as an abrupt decline in renal function, clinically manifesting as a reversible acute increase in nitrogen waste products—measured by blood urea nitrogen (BUN) and serum creatinine levels—over the course of hours to weeks.. It is one of the common and dramatic syndromes encountered in clinical practice. Gastroenteritis is inflammation of stomach and small intestine producing nausea, vomiting and diarrhea. Methods: This was a Descriptive study conducted after getting the approval from the hospital ethical management committee after giving details about the study. This study was conducted on 200 patients who were diagnosed with Acute Kidney Injury (AKI) following Acute Gastroenteritis fulfilling inclusion and exclusion criteria, admitted at MGM Medical college & LSK Hospital, kishanganj, Bihar during the period of December 2019 to November 2020. All patients of either sex diagnosed as having acute kidney injury due to gastroenteritis and Presence of clinical manifestations of gastroenteritis were taken for the study. Patients were categorized into Pre-Renal group and ATN group. Detailed history and clinical profile was recorded in these patients. Duration of GE and time period elapsed between GE and development of Acute Renal Failure was recorded. Laboratory parameters such as CBC, Renal function tests, Serum electrolytes, Urine Examination and Stool Examination were done at the time of admission. The clinical and laboratory parameters were analyzed to assess the role of each of these factors as possible outcome (Recovery or Death) Results: The commonest type of renal Injury in our study was acute tubular necrosis 54% and followed by pre renal azotemia 46%. Out of 200 patients 82% survived and 18% expired. 128 patients had diarrhoea less than 5 days with 43.75% in Pre renal and 56.25% in ATN Group and in 72 patients it was > 5 days with 50% in Pre renal and 50% in ATN group. The Range of Urine output was from 0 to 1300ml with an average of 415.7 ± 314.80. 30% had moderate dehydration. The mean interval between onset of GE and development of AKI was 3.14 ± 2.25 days. The mean peak creatinine was 5.478±3.58 with 4.503±3.54 in pre renal and 6.309±3.43 in ATN group. At admission the urea levels ranged between 30 to 401 mg/dl with mean of 150.51±95.68. The Mean peak urea level was 166.24±96.14. Conclusions: Gastroenteritis was one of the leading causes of AKI. Male preponderance was noted. The highest incidence of disease was seen during April to August coinciding with the period of peak incidence of gastroenteritis in tropics. Morbidity was more in patients with higher creatinine levels than those with lower creatinine levels. Hypokalemia is important electrolyte disturbance in ARF due to gastroenteritis. Urinary output and septicemia can be considered as the important prognostic factors for the disease with septicemia being the main cause of death.