Background: Cardiac surgery-associated acute kidney injury is a common and serious postoperative complication of cardiac surgery that employs cardiopulmonary bypass. Acute renal failure occurs in up to 30% of patients who undergo cardiac surgery. Aim of the Work: to compare between the effectiveness of acetylcysteine and bicarbonate in prevention of acute kidney injury in patients undergoing elective cardiac bypass surgeries. Patients and Methods: This interventional prospective comparative randomized single blinded study was conducted on 120 cardiac patients, hypertensive, diabetic with normal preoperative kidney functions, of either sex, aging >40 years old, scheduled for elective cardiac bypass surgery at Cardiothoracic Surgery Department of Ain Shams University hospitals. Study started June 2017 and ended December 2018; after the approval of the ethical medical committee and obtaining a written informed consent from the
patient. Results: The current study showed nonsignificant correlation between usage of NAC and bicarbonate and renal protection after cardiac bypass surgeries. Also the current study showed the more the time of aortic clamping, time of CPB and the lower the MAP during CPB, the more the rise in serum creatinine after 24 hours. Conclusion: The current study shows that perioperative intravenous administration of NAC with or without sodium bicarbonate may not have a role in prevention of acute kidney injury in patients undergoing elective cardiac bypass surgeries as detected by serum creatinine and creatinine clearance.