Objectives: Our aim is to compare between the effects of intraoperative intravenous N-acetylsysteine infusion to intravenous prostaglandin E1 infusion for prevention of renal injury in patients undergoing abdominal aortic surgery with infrarenal aortic cross clamping. Patients and Methods: After approval of our Departmental Ethics and Research Committee, written informed consents were obtained from patients. Thirty patients were enrolled in the controlled randomized study. There were 26 male and 4 female patients with a mean age of 52.056 ±9.40 years scheduled for abdominal aortic surgery with infrarenal aortic cross-clamping with normal preoperative serum creatinine level (<1.5 mg/dl). ), patients were randomly assigned into three equal groupseach containing 10 patients as follows: Control group in which patients were received saline infusion at a rate of 2 ml/Kg/h after skin incision till 30 min after aortic de-clamping, NAC group in which patients were received N-acetylcysteine(FLUIMUCIL® 5g/25ml,Zambon)after skin incision at a dose of 150mg/kg infused in 20 min, followedby an infusion of 20 mg/kg/h till 30 min after aortic de-clamping, and PGE1 group in which patients were received PGE1 (PROSTIN*VR, 0.5mg/mL, Pfizer) after skin incision at a dose of 20 ng/Kg/min till 30 min after aortic de-clamping. Demographic data including patient’s age, weight, gender, ASA score, co-morbidities and indication for surgery were recorded. Patients’ vital signs were monitored before induction of anesthesia as a baseline till 72h postoperatively and it were recorded for this study at the baseline, 5 min after induction, 5 min after starting study drug infusion, 5 min after aortic cross clamp, 5 after removal of the clamp, 5 min before discontinuation of inhaled anesthetics, 12h, 24h, 48h and 72h thereafter postoperatively. These vital signs included heart rate, invasive mean arterial blood pressure, CVP, Spo2. The total duration of surgery (started from skin incision till skin closure) and the total duration of infra-aortic cross clamping were also measured. Total amount of fluids and blood products given during surgery were also recorded. The amount of urine output intraoperatively and the amount of urine output every 12 h during the 1st 72 h postoperatively was collected and measured.Any diuretic use and its dose during the 1st 72 h postoperatively were also recorded. Blood samples for measurement of plasma creatinine were taken preoperatively then it was repeated at 6h, 24h, 48h and 72h postoperatively. Cystatin C and urinary albumin/creatinine ration were measured before aortic clamping as a baseline the repeated at 24 h postoperatively. Serum creatinine based monograms and urine creatinine and urinary albumin were analyzed using routine laboratory methods. Cystatin C was measured using an automated system. The1ry endpoint in this study was acute kidney injury as indicated by presence of any of the following: Fulfilling one or more of RIFLE criteria namely; doubling of serum creatinine, reductioin urine output < 0.5 ml/h over 12 h, reduction in glomerular filtration rate >50% which is calculated using Cockcroft-Gault formula every 24 h for the 1st 72 h postoperatively. Or elevated serum cystatin C level over 1.4 mg/litre. Or elevated urinary albumin creatinine ratio (as an indicator of glomerularinjury) >300 mgalbumin/g creatinine. Secondary endpoints were: ICU mortality, ICU length of stay(LOS) and possible postoperative complications including abdominal re-exploration during the 1st 72h after surgery for bleeding or for lower limb ischemia and percent of patients needed vassopressors or inotropes. Results: There were no significant statistical differences between the three studied groups as regarding renal protection in that type of patients. Conclusion:Acute renal injury is a reported complication following abdominal aortic surgery with infra-renal aortic cross-clamping. Although the mentioned role of N-acetylcysteine and prostaglandinE1in prevention ofrenal injury, wecould not find an evidence of that role in our study population. The principal measure for prevention of acute kidney injury in these patient remained adequate hydration with maintenance of a good perfusion pressure and avoidance of nephrotoxic agents. It is recommended that, to repeat the study on large scale patients with extending the study drugs’ infusion time to reach 24 h. Also, it is recommended to repeat the study on patient who required supra-renal clamping of the aorta as the incidence of renal injury in these patients is higher than those with infra-renal clamping.