OBJECTIVE: To evaluate the effects of Shendan Jianyi Capsule (SDJYC) on aldose reductase (AR) activity of the kidney in diabetic rats and the significance of prevention and treatment of diabetic nephropathy with Chinese natural herbs. METHODS: Diabetic Wistar rats were treated with SDJYC and sorbinil respectively, and the AR activity in kidney, urine protein and the activity of Na(+)-K(+)-ATPase were tested. RESULTS: The AR activity in diabetic rats was decreased obviously after being treated with sorbinil or SDJYC. The activity of Na(+)-K(+)-ATPase in diabetic rats decreased obviously at the end of the eighth week, and increased after being treated with sorbinil and SDJYC. There was no difference between two treated groups after the treatment. It demonstrated that the inhibition of AR activity could improve the activity of Na(+)-K(+)-ATPase and SDJYC had the same effect. CONCLUSIONS: SDJYC exerts effects by inhibiting the activity of AR.