Objective: We examined the prevention and cure effect of the Alcohol extract of spica prunellae (AEP) on experimental diabetic nephropathy in rat. Methods: The AEP was obtained by extracting spica prunellae with ethanol and chloroform. After 4 weeks experimental diabetic model was induced by i.p. rats streptozotocin(STZ), DM rats were administratred the AEP 100mg·kg -1 ,200mg·kg -1 for 4 weeks, blood glucose, kidney function and activity of kidney aldose reductase were determined. Results: The AEP decreased significantly urinary protien in diabetic rats. The AEP 100mg·kg -1 decreased blood urea nitrogen(BUN) and creatinine(Cr) in diabetic rats. The AEP deceased significantly activity of kidney aldose reductase in diabetic rats. Conclusions: The AEP had certain degree of preventing diabetic nephropathy. The results suggested that the AEP defect diabetic nephropathy by inhibiting activity of aldose reductase to decrease associated tissue or organ injuries caused by accumulation of sorbitol.