Objective To observe effect of Paidu Baoshen Wan（ PDBSW） on renal fibrosis of rats with 5 /6nephrectomy and to discuss the underlying mechanism. Methods Fifty SD rats were randomized into normal group

sham-operation group

model group

PDBSW group and Niaoduqing Granules（ 尿毒清颗粒

NDQG） group

with 10 rats in each group. Excluding normal group and sham-operation group

the others received 5 /6 nephrectomy to make renal fibrosis model. The PDBSW group and the NDQG group were respectively given PDBSW 1. 0 g /（ kg·d） and NDQG 3. 33 g /（ kg·d） by gavage

while the normal group

the sham-operation group and the model group were given normal saline 2 ml / d by gavage. Four weeks later

killed rats and collected remnant nephridial tissue to observe pathology stained by HE

PAS

PASM

Masson

and then to test expression level of protein and mRNA of transforming growth factor β1（ TGF-β1）

Smad2 and Smad7. Results In the model group

topo-segmental glomerulus ischemic atrophy occurred

with much inflammatory cell infiltration and mild to moderate fibrosis. Compared with the model group

the degree of remnant nephridial lesion decreased in PDBSW group. Compared with the normal group and the sham-operation group

expression levels of protein and mRNA of TGF-β1

Smad2 increased markedly in the model group

while those of Smad7 decreased markedly（ P < 0. 01）. Compared with the model group

expression levels of protein and mRNA of TGF-β1

Smad2 in the PDBSW group and the NDQG group decreased markedly

while those of Smad7 increased markedly（ P < 0. 01）. Conclusion PDBSW may help resist renal fibrosis. These effects may be due to reducing expression of TGF-β1 and Smad2

meanwhile increasing expression of Smad7 in nephridial tissue.