Objective:To investigate the effects of Yishen Xiezhuo Huayu Decoction on chronic renal failure（CRF） in model rats and explore its action mechanism.Methods: Rats were randomly divided into the traditional Chinese medicine（TCM） Yishen Xiezhuo Huayu Decoction group

the Western medicine enalapril maleate group

the model group and the sham group.The CRF model was induced by 5/6 subtotal nephrectomy in rats.The blood levels of urea nitrogen（BUN）

creatinine（Cre）

nitric oxide（NO）

endothelin（ET）

clacitonin gene-related peptide（CGRP） and pathological changes of residual kidney were detected.Results: Following treatment

the blood levels of BUN and Ser of both the TCM group and the Western medicine group significantly declined compared with those of the model group（P<0.01）;moreover

the decline in the TCM group was more remarkable than in the western medicine group（P<0.05）.Compared with the sham group

the blood levels of ET and CGRP of the model group significantly rose（P<0.01）.Both the drugs studied could effectively lower the blood level of ET and the decreasing extents were significant in both the TCM group（P<0.01） and the Western medicine group（P<0.05） when compared with the model group.The blood level of CGRP of the TCM group also declined（P<0.05）.There were no significant differences in the blood level of NO of each group.The most severe pathologic changes in renal tissue were observed in the model group and Yishen Xiezhuo Huayu Decoction could alleviate the changes more effectively than enalapril maleate.Conclusion: Yishen Xiezhuo Huayu Decoction can protect renal functions of CRF rats more effectively than enalapril maleate.The action mechanism of the TCM might include the down-regulation of the blood ET level

and the alleviation of pathologic changes of renal tissues.