Abstract： AIM:To investigate the therapeutic effects of soybean isoflavones on osteoperosis.METHODS:Twenty-four male rats were randomly assigned into 3 groups:group A,as the control,were implemented sham surgery on the bilateral testieular;group B were treated with bilateral testieular ablation;group C were animals with bilateral testieular ablation and treated with soybean Boflavones.After 8-week treatment,the rats were sacrificed and the the trabecula of lumbar and tibial epiphyseal extremity was observed and the percentage of trabecula was determined under microscope.RESULTS:Compared with group A,the trabecula of lumbar and tibial in group B were significantly narrow,and spaces between trabeeulas became markedly wider.Also,percentages of trabeculas under microscope visual field decreased,and trabeculas were frequently broken.However,osteoporosis denonstrated in group B Was significant ameliorated in group C with development of new cartilage.CONCLUSION:Soy isoflavones have therapeutic effects on osteoporosis in bilateral testieular-ablated rats.