Objective To explore the possible mechanism of Zuogui Pill（ 左归丸） and Yougui Pill（ 右归丸） in treating postmenopausal osteoporosis（ PMOP）.Methods Sixty rats were randomized into a blank group

a sham operation group

a model group

an estradiol valerate tablets group

a Zuogui Pill group and a Yougui Pill group

10 rats in each group.Except the blank group and the sham operation group

rats in other groups were built PMOP models by bilateral oophorectomy.After 3 days

the Zuogui Pill group

Yougui Pill group and estradiol valerate tablets group were given corresponding medicine by gavage

with the dose of 9.45 g /（ kg·d）

10.26 g /（ kg·d）

and 0.09 g /（ kg·d）

respectively.The blank group

the sham operation group and the model group were given 2 ml of distilled water by gavage.All groups were treated for 12 weeks.After intragastric administration was over

morphological changes of bone in proximal femur was examined by hematoxylin and eosin stain（ HE stain）.The expressions of femur bone marrow peroxisome proliferator activated receptorsγ（ PPARγ）

CCAAT-enhancer binding proteinβ（ C /EBPβ） and CCAAT-enhancer binding proteinα（ C /EBPα） were detected with Western blot method.Results Compared with the blank group

fat cells in the femur

and the expressions of bone marrow PPARγ

C / EBPβ and C / EBPα proteins in the model group increased（ P < 0.01）.Compared with the model group

fat cells in the femur

and the expressions of bone marrow PPARγ

C / EBPβ and C / EBPα proteins in the estradiol valerate tablets group

the Zuogui Pill group and the Yougui Pill group decreased to varying degrees

especially in the estradiol valerate tablets group and the Zuogui Pill group（ P < 0.05 or P < 0.01）.Conclusion Zuogui Pill and Yougui Pill might both improve the bone marrow microenvironment of ovariectomized rats.The mechanism might relate to inhibiting the femur adipose differentiation and the expressions of bone marrow PPARγ

C / EBPβ and C / EBPαproteins.