Objective： To investigate the expression and orientation of decorin in renal biopsy and to investigate the correlation between decorin and TGF-β1 and renal tubulointerstitial fibrosis. Methods：The pathological and clinical data of 36 patients with glomerulonephritis and tubulointerstitial diseases were collocted, and divided into different groups according to serious degrees. The expression and orientation of decorin and TGF-β1 in the renal tissue were detected by immunochemistry. Results：Decorin was mainly expressed in renal tubular epithelial cells, especially in epithelium of proximal tubule. With the development of tubulointerstitial lesions, the expression of decorin was increased. TGF-β1 was mainly expressed in renal tubular epithelial cells, and there was no differece between proximal tubule and distant tubule. The expression of TGF-β1 was also increased with the development of tubulointerstitial lesions. A positive correlation was found between decorin and TGF-β1 in renal tubule. Conclusion：Decorin can take as an indicator to response the tubulointerstitial damage, at the same time, it can reduce the expression of TGF-β1 in some degree.