The primary goal of the trial was to evaluate whether the optimal antiproteinuric doses of benazepril (an ACE inhibitor) or losartan (an ARB), as compared with their conventional doses, can safely improve the long-term renal outcome in nondiabetic patients with proteinuria and chronic renal insufficiency. The second aim was to compare the long-term renal protection between benazepril and losartan at similar clinical setting.

Inclusion Criteria:

1. Serum creatinine concentration of 1.5 to 5.0 mg per deciliter (133 to 442 µmol/L)
2. Creatinine clearance of 20 to 70 ml per minute per 1.73m2, with variations of less than 30 percent in the three months before screening evaluation
3. nondiabetic renal disease
4. Persistent heavier proteinuria (defined by urinary protein excretion of more than 1.0 g per day for three or more months without evidence of urinary tract infection or overt heart failure [a New York Heart Association class of Ⅲ or Ⅳ])

Exclusion Criteria:

1. Immediate need for dialysis
2. Treatment with corticosteroids, non steroidal anti-inflammatory drugs, or immunosuppressive drugs
3. Hyper-or hypokalemia (serum potassium concentration 5.6 mmol per liter or more，or 3.5 mmol per liter or less)
4. Renovascular disease
5. Myocardial infarction or cerebrovascular accident in the year preceding the trial
6. Connective-tissue disease; and obstructive uropathy