Objective: To study the treating effect on early closed fractures using Taohong Siwu Tang (TST). Method: Sixty SD rats were randomly divided into six groups:normal group

model group

TST-treated group (18

9

4.5 g·kg-1) and Shenxiang Jiegu group (0.6 g·kg-1). The tibia closed fracture model rats were created using a dedicated fracture pusher. The influence on blood viscosity of TST was observed. The plasma thromboxane (TXB2) and 6-ketone prostaglandin (6-keto-PGE1α) content were detected by RIA

the serum vascular endothelial growth factor (VEGF) content was assayed by ELISA. The situation of callus microvascular and fracture healing were observed using bone biopsy. Result: Compared with the normal group

model group showed severity of fracture defects and the blood viscosity increased significantly (P<0.01). Additionally

both plasma TXB2 and TXB2/6-keto-PGF1α elevated markedly (P<0.01)

and the content of VEGF increased slightly. Compared with the model group

all doses of TST groups could significantly stimulate the regeneration of blood vessel of callus in early phase and promote the healing of fracture. Meanwhile

it could reduce blood viscosity of fracture in rats

decrease the levels of plasm TXB2 and TXB2/6-keto-PGF1α significantly and increase the level of serum VEGF obviously (P<0.05

P<0.01). Especially

the effect of high dose group is close to the effect of positive drug group (P<0.01). Conclusion: TST has good stasis-removing and regeneration-promoting effect on early closing fractures

the mechanism may be related to decreasing the levels of plasm TXB2 and 6-keto-PGE1α

increasing the level of serum VEGF.