['Renal ischemia-reperfusion (I/R) injury may occur after renal transplantation, thoracoabdominal aortic surgery, and renal artery interventions.', 'To investigate the therapeutic effects of aprotinin on tissue protection against I/R injury in a rat model. N-acetylcysteine (NAC), a potent antioxidant, was also tested to assess the experimental model.', 'Twenty-four rats were categorized into 3 groups of 8 rats each: those receiving isotonic sodium chloride solution (control group); NAC, 150 mg/kg; and aprotinin, 40,000 KIU/kg. The animals underwent unilateral nephrectomy after 60 minutes of warm ischemia and 60 minutes of reperfusion of the kidney. Malondialdehyde, a lipid peroxidation marker, and antioxidant glutathione levels were measured in the kidney parenchyma. Tissue samples were obtained for histologic analysis.', 'Compared with the control group, the NAC group demonstrated significantly low levels of malondialdehyde (P = .04) and high levels of glutathione (P = .01). At histopathologic analysis, less acute tubular necrosis (ATN) and cellular swelling was noted in the NAC group (P = .002 and P = .005, respectively). In the aprotinin group, histopathologic analysis revealed less tissue damage in terms of ATN (P < .001, cellular swelling (P < .001), and vacuolysis (P = .002). Compared with the NAC group, ATN (P = .01), vacuolysis (P = .04), and congestion (P = .05) were significantly less in the aprotinin group.'] Does serine protease inhibitor aprotinin ameliorate renal injury in a rat model of ischemia-perfusion injury?