OBJECTIVE To investigate the molecular mechanisms of resveratrol( Res)in renal interstitial fibrosis(RlF)in rats with unilateral ureteral obstruction(UUO). METHODS Forty-eight Spra-gur-Dawley rats were randomly divided into UUO( normal saline,n = 16),UUO with Res treatment (Res,20 mg·kg-1 ,n=16),and sham-operation(sham,n=16)models. The kidneys were excised on the 7th and 14th day. The deposition of collagen fiber in the kidney was detected with HE and Masson staining. The levels of sonic hedgehog(SHH,an inducer of SHH pathway)in kidney tissues were deter-mined by ELlSA. lmmunohistochemical analysis was performed to evaluate the protein expression of SHH signaling-related molecules,including SHH,smoothened(Smo),patched-1(Ptch1),and Gli1, proliferating cell nuclear antigen(PCNA)and matrix component typeⅢ collagen. The mRNA expression levels of Smo,Ptch1 and Gli1 were detected by real-time RT-PCR. RESULTS The degree of RlF observed with HE and Masson staining was obviously increased in UUO kidneys,but decreased in Res-treated kidneys. Enhanced expression levels of typeⅢ collagen and PCNA in UUO rats were suppressed by Res treatment(P﹤0.05). Res administration decreased the expression levels of SHH,Smo,and Gli1 (P﹤0.05),but increased the expression of Ptch1(P﹤0.05),suggesting that Res inhibit the obstruction-induced activation of SHH signaling. CONCLUSION Res can attenuate RlF in UUO rats,and the possi-ble mechanism is that Res down-regulates the activity of SHH signaling and inhibits cellular proliferation, resulting in inhibition of matrix accumulation in renal interstitium of UUO rats.