Although the cardiovascular actions of calcium antagonists have been studied extensively, it is only recently that attention has focused on the effects of calcium antagonists on renal function. Variable actions of calcium antagonists on renal hemodynamics have been observed when these agents are used in experimental animal models. In contrast, when administered in vitro to the isolated perfused kidney, calcium antagonists demonstrate more predictable actions. Calcium antagonists do not affect the vasodilated isolated kidney, but they do dramatically alter the response of the kidney to vasoconstrictor agents. In the presence of norepinephrine, calcium antagonists produce a modest improvement in renal perfusion and significantly augment glomerular filtration rate. This preferential augmentation of glomerular filtration rate may be attributable to a selective vasodilation of pre-glomerular vessels. Although the clinical implications of such observations are not yet clear, preliminary studies indicate that calcium antagonists may exert salutary effects on renal function in clinical settings that are characterized by impaired renal hemodynamics. The possible benefits of calcium antagonists in ameliorating the development of renal dysfunction in patients in whom there is increased risk for the development of acute renal insufficiency remain to be evaluated.