Many patients with arterial hypertension have abnormal urinary excretion levels of albumin. This study was aimed at examining the effects of lisinopril and amlodipine on urinary excretion of albumin and kidney function. Thirty-six previously untreated patients with essential arterial hypertension were divided randomly into two groups. The first group received lisinopril 20 mg daily for 12 weeks followed by 10 mg amlodipine daily for another 12 weeks. The second group received 10 mg amlodipine daily for 12 weeks followed by 20 mg lisinopril daily for another 12 weeks. The arterial pressure decreased in a similar way with both therapies in both groups. In both groups urinary albumin excretion decreased in patients receiving lisinopril (p < 0.01). No significant changes were observed with amlodipine. This study shows that lisinopril, but not amlodipine, is able to reduce urinary excretion of albumin in patients with essential hypertension independently of its effective antihypertensive properties. It is probable that the positive effect of lisinopril on microalbuminuria is attributable to the modifications in intrarenal hemodynamics or to a change in glomerular permeability.