The preventive effect of Salvia miltiorrhiza extracts (SM) with or without high molecular weight soluble kitosan (K) on the progress of bone loss induced by ovariectomized (OVX) was studied in rats. From light microscopic analyses in histochemistry data, trabecular bone area in OVX rats was significantly decreased compared with that in sham rats. The decrease was regulated by administration of SM and especially the combination of SM and K (SM + K) for 7 weeks. In addition, the numbers of osteoblasts and osteoclasts were regulated in SM + K-administered rats but not different from those in either SM or K-administered rats. In OVX rats, free Triiodothyronine ($T_3$) and Thyroxine ($T_4$) were similar to control, ruling out the involvement of abnormal thyroid hormone. Although serum calcium is similar among all the groups, estrogen level was higher especially in SM+K-administered rats. These results strongly suggest that SM+K are effective in preventing the development of bone loss induced by OVX in rats.