Objective To investigate the effects of benazepril on the blood pressure and urinary protein in AT1-adrenergic receptor positive hypertension patients with diabetic nephropathy(DN).Methods The synthesized epitopes of the second extracellular loop of AT1 receptor (165-191) was used to screen serum autoantibodies from hypertension patients with DN (n=71),diabetic mellitus(n=51) and from healthy blood donors (n=40, control) by ELISA. The patients in autoantibodies against AT1 receptor positive group (n=31)and negative group(n=40) were given the following drugs repectively: benazepril (10mg/d), aspirin(100mg/d), nitrendipine(10mg/d). The blood pressure reducing effect was compared between the groups.The 24-hour urinary protein were measured before and after treatment for 24 weeks.Results In hypertension patients with DN, the positive rate of the autoantibodies against AT1receptor was 43.7%(31/71), and was significantly higher than that in the diabetes mellitus patients(13.7%,7/51)and healthy blood donors(10%,4/40,P<0.01). The total efficiency rate of benazepril treatment in reducing blood pressue was significantly higher in autoantibodies against AT1 receptor positive group than that in negative group (85.6% vs 45.0%,P<0.01). The total efficiency rate of benazepril treatment in reducing urinary protein was significantly higher in autoantibodies against AT1 receptor positive group than that in negative group (87.1% vs 42.5%,P<0.01).Conclusion Benazepril can reduce urinary protein more significantly in hypertension patients with DN and positive autoantibodies against AT1 receptor than that in those with negative autoantibodies against AT1 receptor. Benazepril is effective and safe in the treatment of hypertension with DN.