The present study was aimed to investigate whether glycyrrhizin, which is the major component of Glycyrrhiza uralensis, has an antioxidant effect and regulatory effect on Na,K-ATPase in gentamicin-induced acute renal failure (ARF) rats . It is well known that reactive oxygen species (ROS), such as superoxide anion and hydroxyl radical, are main pathophysiological factor in gentamicin-induced ARF. Glycyrrhizin showed potent in vitro antioxidant activity, especially superoxide scavenging activity, in a dose-dependent manner. Plasma lipid peroxide level was restored to normal level by oral administration of glycyrrhizin (200 mg/kg) in the gentamicin-induced ARF rats. The expression of Na,K-ATPase α1 subunit was restored in the gentamicin-induced ARF rats by administration of glycyrrhizin, whereas β1 subunit was not restored. The renal functional parameters including urine volume, cleatinine clearance, urine osmolality, solute-free water reabroption were also partially restored in gentamicin-ARF rats by administration of glycyrrhizin. Taken together, the amelioration of renal functions and the expression of sodium pump by administration of glycyrrhizin in the gentamicin-induced ARF was appear to be mediated by the scavenging of ROS.