The objective of this study was to investigate in vivo effects of lipoic acid (LA) in preventing steroid-induced osteonecrosis and the possible pathway in a rabbit model. Sixty rabbits were divided into 2 groups: rabbits were intraperitoneally injected with LA aqueous solution at 36 mg/kg of body weight per day for 4 weeks in Group A and rabbits were injected with physiologic saline (PS) as a control in Group B. At 2 weeks after starting treatment, they were intramuscularly injected once with 20 mg/kg of methylprednisolone acetate (MPSL). The femora were histopathologically examined for the presence of osteonecrosis. The plasma levels of total cholesterol (TC), low-density lipoprotein (LDL), high-density lipoprotein (HDL), glutathione (GSH), endothelin (ET) and malondialdehyde (MDA) were assayed at 2 weeks after the injection of MPSL. The incidence of osteonecrosis was significantly higher in Group B (73.1%) than in Group A (20.8%). The GSH level was higher in Group A than in Group B after the LA injection. The plasma MDA and ET levels were lower in Group A than in Group B at 2 weeks after the MPSL administration. Lipoic acid can prevent the development of steroid-induced osteonecrosis in rabbits. Inhibited oxidative stress and amendment of vascular endothelial dysfunction is a possible mechanism for this effect.