Objectives : The present study was carried out to investigate the beneficial effect of Coicis Semen extract(CSe) on streptozotocin(STZ)-induced diabetic nephropathy rats. CSe was given to rats with oral administration. Methods : The experimental animals were divided into 3 groups : normal group of rats, control group of STZ-induced diabetic rats, sample group with CSe treatment. Experimental diabetes was induced by the injection of STZ(60 mg/kg) to the rat via the peritoneum. The effects of CSe on STZ-induced diabetic nephropathy were observed by measuring the serum level of creatinine, BUN and uric level of glucose. Kidney level of lipid peroxidation and the activities of reduced glutathione(GSH) were also examined Results : STZ-induced increase of serum creatinine was lowered by CSe treatment, but BUN and uric level of glucose did not show significant changes. CSe oral administration showed statistical decrease of lipid peroxidation in renal cortical tissues, but it has no effect on the activities of GSH. Conclusion : CSe treatment showed protective effect on rat diabetic nephropathy model, but action mechanism of the effect was still not dear. We thought to be concerned with anti-oxidative stress.