Abstract: AIM: To investigate the role of Chinese herb medicine in improving the changes of bone mass, bone biomechanical properties and hemorheological pa-rameters under simulated weightlessness.METHODS: 120 ratswere divided into 6 groups:control group, head down tilts -30°group (HDT), Danhuangci group (HDT +Dansheng, Huangqi, Ciwujia), Shenchuanshu group (HDT + ginseng, Chuanxiong, Shudi), Shenshandu group (HDT + American ginseng, Haw, Duzhong), and Shenyingsheng group (HDT +ginseng, the leaves of gingkgo, Shengdi). The bone mineral content, bone biomechanical properties and hemorheological parameters were observed following HDT for 30 days.RESULTS: After 30 day HDT, the body weight of rats, content of bone mineral salt, biomechanical indices, and the area of cortex decreased. The blood viscosity in low and middle shear, plasma fibrinogen and the rate of erythrocytes with abnormal shape increased significantly, and erythrocyte deformability (DImax, IDI) and hematocrit (HCT) de-creased.Chinese herb medicines were available to im-prove the hemorheological parameters and some bone biomechanical indices.CONCLUSION: Chinese herb medicines are effective to prevent the changes of blood circulation and bone properties under simulated weight-lessness.

Key words: simulated weightlessness, hemorheologi-cal parameters, bone loss, countermeasure