The increasing incidence of steroid-induced osteonecrosis of the femoral head is a recent and emerging problem. In-depth pathogenesis, however, has not been well understood. We focused on oxidative stress, which was reported to be involved in many diseases, and conducted animal studies to investigate it. Our results from the rabbit model of steroid-induced osteonecrosis demonstrated that administration of steroids caused oxidative damage in bones, and the administration of glutathione reduced the incidence of osteonecrosis. We were also the first to have successfully induced osteonecrosis in rats by administering buthionine sulfoximine (BSO) . The results indicated the involvement of oxidative stress in the development of osteonecrosis and may contribute to elucidating the underlying mechanisms and prevention of the pathogenesis of steroid-induced osteonecrosis.