The purpose of this study is to demonstrate the renoprotective effect of the ARBs in patients with nephropathy due to type 2 diabetes or hypertension. We administered three kinds of treatment regimens to patients with type 2 diabetes and/or high blood pressure who also exhibited microalbuminuria: the first with ARBs, the second with ACE inhibitors and the third with both. After a course of 24 weeks of treatment with ARBs, we demonstrated a significant improvement of the microalbuminuria, but the combined type of therapy was the most effective. The fall in blood pressure did not show a significant difference among patients groups. In conclusion, this pharmacologic group offers a great deal of renal protection, which shows an independent pattern to the blood pressure decreasing effect.