To make a systematic assessment on whether the progression of early diabetic renal disease with normotension may be slowed down by angiotensin-converting enzyme (ACE) inhibitors. Methods: Randomized clinical experiments published on MEDLINE from January 1990 to April 1999 and on China Biological Medicine were reviewed for studying the effects of ACE-inhibitors on normotensive patients with early diabetic renal diseases. Based on the inclusion criteria, 10 studies were selected. Their results were combined and analyzed with RevMan3.1 software.Results: The pooled effect of urinary microalbumin excretion rate, systolic blood pressure, diastolic blood pressure and mean arterial blood pressure were -77.502 mg/24 h [-100.748 to-54.256], -5.002 mmHg [-9.630 to 0.685], -2.949mmHg [-4.005 to 1.892], -4.284 mmHg [-5.444 to 3.123] respectively. Using clinical albuminuria as the end-point. The pooled odd ratio was 0.27 [95% CI 0.18 0.40]. The sub-group analysis showed that those results had no difference between type 1 and type 2 diabetes. There was no significant correlation between the pooled effects of urinary micro-albuminuria excretion rate and systolic blood pressure, diastolic blood pressure or mean arterial blood pressure. Conclusion:ACE inhibitors can decline urinary micro-albuminuria excretion rate in normotensive patients with early diabetic renal disease and delay the progression of early diabetic renal disease to clinical albuminuria. These effects may not be dependent on its blood pressure-reduction effect.