Recent clinical trials have indicated the utility of mineralocorticoid receptor (MR) antagonists in patients with cardiovascular and renal diseases. Experiments studies have shown that chronic treatment with aldosterone resulted in severe cardiac and renal injuries, which were ameliorated by MR antagonists. In vitro studies also showed that MR is highly expressed in cultured vascular endothelial cells, vascular smooth muscle cells, cardiomyocytes, mesangial cells, glomerular epithelial cells, renal fibroblasts and proximal tubular cells. In these cells, aldosterone-induced cell injuries were prevented by MR antagonists. These accumulating data support the notion that aldosterone is involved in the pathogenesis of cardiovascular and renal injuries through local MR activation.