Background Cardiac surgery-associated acute kidney injury (CSA-AKI) is an important and serious complication that affects morbidity and mortality. We studied both pediatric and adults using the definition of the Acute Kidney Injury Network (AKIN). Methods This is an observational retrospective cohort study done at King Abdulaziz University Hospital in Jeddah, Saudi Arabia approved by ethical committee. The exclusion criteria were baseline serum creatinine (SCr) ≥ 4 mg/dL or preexisting renal failure requiring dialysis, reoperation, death within 24 hours postoperatively, and operative mortality or missing data. 941 patients were included in the analysis using the statistical software  SPSS, version 15.0. Results 28.68% in the adult group and 20.07% in the pediatric group developed CSA-AKI. Adult risk factors included age group of 60-69 years, cardiopulmonary bypass (CPB), number of grafts and hypertension. In the pediatric group, CPB, aortic cross-clamping (ACX) and the lower preoperative SCr are the main risk factors Conclusion Conventional conservative management and preoperative Identification of predictor risk factors are essential for prevention of CSA-AKI which constitute the main strategy for optimal management.