The natural course of essential hypertension, and hypertension associated with advanced renal parenchymal disease, is characterized by a progressive deterioration of renal function. If calcium antagonists can control both systemic and glomerular hypertension, they may be able to attenuate this process. Short-term studies in our laboratory suggest that the calcium antagonists amlodipine, diltiazem, and nifedipine preserve and/or improve renal function; there were no adverse effects on glomerular filtration, effective renal plasma flow, and/or urinary protein excretion. However, long-term clinical trials are required to determine if the observed short-term renal responses are sustained and if calcium antagonists protect the human kidney from systemic and glomerular hypertension.