The effect of treatment with enalapril (10 days at 10 mg/d followed by 4 weeks at 20 mg/d) on forearm hemodynamics was assessed in eight normotensive patients and eight patients with hypertension affected by Type II diabetes as well as in eight patients with essential hypertension and normal glucose tolerance. The ACE inhibitor decreased regional vascular resistances and increased the maximum arteriolar-vasodilating capacity and venous distensibility in the three groups of patients. Thus, this study shows that ACE inhibition by enalapril improves regional hemodynamics in patients with Type II diabetes.