The presence of proteinuria has been shown to be an excellent predictor for a worse outcome of renal function. Both proteinuria and arterial hypertension often coexist in the same patient, and therapy must be directed at decreasing protein excretion in the urine as well as lowering the blood pressure. Any antihypertensive agent has the capacity to lower proteinuria simply by lowering blood pressure. Furthermore, the antiproteinuric capacity of angiotensin-converting enzyme inhibitors can be equalized by other agents or their combination, provided that the fall in blood pressure is great enough. For this reason studies are needed in which the strict control of arterial hypertension combined with a decrease in proteinuria are considered.