AIM: To investigate the influence of Fructus Arctii and its extracts to the renal pathological changes of diabetic rat and its protective mechansim METHODS: The rat model induced by 55mg/kg STZ once intraperitoneally was adoped as the diabetic nephropathy of early stage, the extract and the powder of Fructus Arctii were given to the diabetic rat for six weeks. We observed the changes of general condition, and examined the expressions of TGF-? 1 (transforming growth factor-? 1) mRNA and MCP-1mRNA (monocyte chemoattractant protein-1) by reverse transcription-polymerase chain reaction (RT-PCR). CONCLUSION: The ethanol extract of Fructus Arctii relieved renal pathological changes of diabetic rat. The mechanism perhaps was related to the reduction in the expression of MCP-1mRNA and TGF-? 1mRNA in kidney; The study proved that the ethanol extract of Fructus Arctii was more effective than its water extract and coarse powder.