Acute kidney injury (AKI) is an abrupt or rapid decline in renal function as evidenced by a rapid rise in serum creatinine (SCr) or decrease in urine output. AKI occurs in children. The aim of the study is to document the epidemiology of AKI in our setting. This was a prospective cross-sectional observational study of all the admissions at the children emergency room of Federal Medical Center in Asaba, Delta State. A diagnosis of community-acquired AKI was made using the pRIFLE criteria if there was a 25% decrease in estimated creatinine clearance from the premorbid baseline (if known) or assumed baseline of 100 mL/min/1.73 m2 and/or urine output <0.5 mL/kg/h for >8 h within the 48 h of admission. There were 404 admissions during the period and those with AKI were 58, giving an incidence rate of 14.4 cases per 100 children aged between >1 month and 16 years. The mean age of the subjects with AKI was 35.7 months. Subjects with AKI stages R (risk), I (injury), and F (failure) were, respectively, 44.8%, 39.7%, and 8.6%. The most common causes were acute gastroenteritis (36.2%), complicated malaria (10.3%), and primary renal disease (10.3%). Age group and sickle cell anemia predicted AKI in these subjects. For the outcome of the AKI, two (3.4%) died, while 55 (96.6%) subjects were discharged alive. The level of SCr within 48 h of admission predicted the outcome of AKI. The prevalence of AKI is high, gastroenteritis being the most common etiology.