Microalbuminuria in patients with essential hypertension is associated with increased incidence of cardiovascular morbidity and mortality. Reduction of urinary albumin excretion (UAE) with therapy could reduce cardiovascular events. The long-term effect of commonly used antihypertensive agents on UAE has not been properly investigated. In the present study, we have prospectively studied the effects of therapy for 24 months with a converting enzyme inhibitor, enalapril, or a calcium channel blocker, nicardipine, on UAE in 40 patients with essential hypertension and microalbuminuria. Enalapril and nicardipine were equally effective in reducing arterial pressure. However, enalapril decreased UAE from 77.1 +/- 10.4 to 30.4 +/- 7.9 mg/24 h after 1 year, and to 24.7 +/- 4.8 (P < .01) after 2 years of therapy. UAE however, did not change in patients treated with nicardipine (from 65.2 +/- 12 to 73 +/- 14 after 1 year, and to 52.7 +/- 21 mg/24 h after 2 years of therapy). The impact of reducing UAE on overall cardiovascular morbidity and mortality and on future progression of renal failure in patients with essential hypertension remains to be established.