Abstract: Objective　To understand the mechanisms by which dexamethasone induces osteoporosis and Tonifying Kindey Recipe prevents dexamethasone-induced osteoporosis.Methods　Thirty six Wistar rats were divided into three groups: control group was injected with 0.9 % sodium chloride solution; dexamethasone group (DEX) and Tonifying Kindey Recipe group(TKR) were injected with dexamethasone (0.1 mg/100g weight) twice a week， and were administrated water and Tonifying Kindey Recipe (0.32 g/100 g weight) at the same time respectively.After 12 weeks the rats were killed and the total mRNA was extracted from bone. The expression of vitamin D receptor (VDR) was semi-quantified by RT-PCR.Results　The bone mineral density was decreased and the expression of VDR mRNA of the rats in DEX group was increased significantly. The bone mineral density of the rats in TKR was augmented and the expression of VDR mRNA was attenuated compared with DEX group.Conclusion　The up-regulating expression of VDR mRNA by dexamethasone may be one of the mechanisms by which dexamethasone induced osteoporosis.Tonifying Kindey Recipe may prevent dexamethasone-induced osteoporosis by down-regulating expression of VDR mRNA.