['The present study investigated the relationship between mast cells (MCs) and the protein expression of stem cell factor (SCF) and transforming growth factor-β1 (TGF-β1) in the regions of renal interstitial fibrosis with protein-overload nephropathy, in order to provide a good animal model to study the mechanism of renal fibrosis induced by proteinuria.', '60 male Sprague-Dawley rats were divided into a bovine serum albumin (BSA) group and a control group. The intensity of MCs infiltration was examined by toluidine blue and chymase and tryptase staining. The protein expression of SCF and TGF-β1 was respectively examined by immunohistochemical and immunofluorescence staining.', 'Severe proteinuria was induced in rats of the BSA group. Expression of SCF and TGF-β1 was detected in the tubular and the interstitial cells. The number of MCs positively correlated with the severity of interstitial lesions and the expression of SCF and TGF-β1.'] Is mast cell infiltration involved in renal interstitial fibrosis in a rat model of protein-overload nephropathy?