Objective: To reveal the mechanism of Zuoguiwan treatment for glucocorticoid induced osteoporosis. Method: Virgin Wistar rats were selected and randomly divided into three groups (n=12-15 per group)

including control group

model group and Zuoguiwan group. The rats were injected dexamethasone (1 mg·kg-1

twice a week) for eight weeks to make the model of osteoporosis

and the Zuoguiwan (9.52 g·kg-1·d-1

6 d per week) was administered intragastrically to the rats in Zuoguiwan group for eight weeks. We analyzed the effect of Zuoguiwan on tibia bone by measuring the relative parameters of the histomorphometric slides of the undecalcified tibia. And the content of bone r-carboxyaluatamic-acid-containing proteins(BGP) and Insulin-like growth factors(IGF- Ⅰ) in serum of rats were detected before and after the treatments. Result: TBV and TFS in model group were decreased significantly

while TRS was increased significantly. And the content of BGP and IGF- Ⅰwere decreased significantly. After being treated by Zuoguiwan

TBV and TFS were increased significantly in Zuoguiwan group

no changes of TRS were observed

while it had the tendency to decrease. The content of BGP and IGF- Ⅰwere increased significantly in Zuoguiwan group. Conclusion: Zuoguiwan can treat glucocorticoid-induced osteoporosis in rats. One of the mechanism is that Zuoguiwan can increase the content of BGP and IGF- Ⅰin serum.