Objective To observe the effect of Yiqi Yangyin Huayu Formula on vascular restenosis after percutaneous transluminal angioplasty for lower extremity and its possible mechanism. Methods Thirty two dogs were randomly divided into model group and high

medium

low dose traditional Chinese medicine（ TCM） groups

with 8 in each. Type 2 diabetic lower extremity vascular restenosis model was established in each group with high fat diet

streptozotocin（ STZ） along with balloon injury.. Since one week before operation

high

medium

and low dose TCM groups were administered with Yiqi Yangyin Huayu Formula 51. 4 g

25. 7 g

or 12. 85 g each time respectively

2 times per week by gavage

while model group was given normal saline

and the treatment lasted for 8 weeks. The blood levels of platelet-derived growth factor（ PDGF）

endothelin（ ET）

nitric oxide（ NO） were monitored before and on the 3rd day

or in the 1st

4th

or 8th week after operation. The vascular samples were obtained in the 5th and 8th week after operation to observe pathological morphology and to perform quantitative analysis on hyperplasia degree. Results Started from the first week after operation

the levels of PDGF and ET declined in all groups

with statistical significance compared with those on the 3rd day post operation（ P < 0. 05）; levels of PDGF and ET in the high

medium

and low dose TCM groups in the 1st

4th

and 8th week after operation were lower than those in the model group（ P < 0. 05）. One week after operation

NO levels were decreased significantly in all groups compared with those on the 3rd day after operation

especially in the model group（ P < 0. 05）; in the 4th and 8th week after operation

NO levels in all TCM groups were higher than that in the model group（ P < 0. 05）. In the 5th and 8th week post-operation

the ratio of vascular intimal hyperplasia area and intima-media area（ IA / MA） of each TCM group was significantly lower than that of the model group（ P < 0. 05）. Also the ratio of vascular intimal hyperplasia area and IA / MA of each TCM group in the 8th week was significantly lower than those in the 5th week（ P < 0. 05）.Conclusion Yiqi Yangyin Huayu Formula may inhabit the vascular intimal hyperplasia by reducing the serum levels of PDGF and ET in postoperative acute phase and increasing the level of NO in long term

so as to prevent the occurrence of lower extremity vascular restenosis in diabetes.