Background:Postoperative acute kidney injury (AKI) is common in patients with chronic liver disease. We prospectively evaluated effectiveness of the N-acetylcysteine (NAC) in preserving postoperative renal functions in cirrhotic patients undergoing major abdominal surgeries.Materials and Methods:A total of 60 cirrhotic patients child A to B were randomized into two groups of 30 each. NAC groupwas received intravenous infusion of NAC (1200 mg/12h starting immediately before surgery and continued for 72h h postoperative) and controls group received a similar volume of glucose 5% solution as a a placebo. Systemic hemodynamics, hepatic and renal functions, serum cystatin C and cystatin C glomerular filtration rate (GFR) (GFR) were compared between both groups.Results:Serum level of cystatin C was raised significantly above the basal value at postoperative day 1 and day 3 associated with significantly decreased in cystatin C GFR below the basal value in the control group (P = 0.001). 6 (20%) (PP = 0.03) in control group developed AKI based on cystatin C GFR criteria (GFR <55 ml/min/1.73m2). Mean values of alanine aminotransferase and aspartate aminotransferase were increased significantly above the basal values in both groups, but the increases were significantly lower in NAC group (P = 0.00). Chest infection was significantly lower associated with shorter hospital stay in the NAC group than the control group.Conclusion:Intravenous administration of NAC NAC in cirrhotic patients undergoing major abdominal surgeries reduces the incidence of cystatin C GFR-based AKI, postoperative renal and liver functions were well-preserved and improved outcome.