The intraperitoneal administration of gentamicin (100 mg kg(-1) day(-1)) to rats is associated with an increased production of malondialdehyde (MDA), which is an end product of lipid peroxidation in the kidney, The level of glutathione (GSH) and the activity of three antioxidant systems-superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx)-were also decreased in the kidney, The liver, however, did not show any such alterations, Gentamicin (100 mg kg(-1) day(-1)) plus lipoic acid administration (25 mg kg(-1) day(-1)) by gastric intubation brought about a decrease in the degree of lipid peroxidation, An increase in the GSH level and in the activity of SOD, CAT and GPx was also observed. From these observations it can be concluded that administration of DL-alpha-lipoic acid prevents lipid peroxidation, which may, at least partly, play an important role in the injury cascade of gentamicin-induced nephrotoxicity. (C) 1997 by John Wiley & Sons, Ltd.