Background: Cardiac surgery associated with acute kidney injury (CSA-AKI) is a common and serious postoperative complication of cardiac surgery requiring cardiopulmonary bypass (CPB). CSA-AKI varies between 7% and 40% in large cohorts undergoing a variety of cardiac surgical procedures and is associated independently with increased morbidity and mortality. Objective: Our study aimed to investigate the effect of using modified ultrafiltration on acute kidney injury by using the levels of AKI biomarkers (serum creatinine and NGAL) in adult patients with no previous chronic renal disease undergoing valvular heart surgery using cardiopulmonary bypass. Patients and Methods: This prospective observational study was conducted at the cardiothoracic surgery unit, Kasr AL-Ainy hospital from February 2017 to July 2017 on 40 patients who underwent valve replacement surgery using cardiopulmonary bypass. The patients were randomly allocated into two groups: Group 1: Non-MUF group. Group 2: MUF group. Results: Regarding serum creatinine, the preoperative and 2h postoperative levels were not statistically different between the two studied groups (P>0.05), while in the non-MUF group, there was a significant increase (P<0.001) in the 2h. post-operative creatinine level compared with the pre-operative level. In the MUF group, there was no significant difference (P>0.05) between AKI and non-AKI patients in preoperative levels while the postoperative creatinine levels were significantly higher (P<0.04) in AKI than non-AKI patients. Conclusion: AKI after cardiac surgery is independently associated with a significant increase in morbidity, mortality, and health-care costs.