MR antagonists have proven to be highly efficient in patients with heart failure and reduced ejection fraction, and they are a cornerstone of contemporary therapy. In the past decade, a series of experimental studies using models with cell type–specific MRs uncovered the cellular and molecular mechanisms underlying its detrimental effect on left ventricular remodeling. Based on these findings, the potential of MR antagonists has been evaluated in other cardiovascular diseases, including coronary artery disease, arterial hypertension, heart failure with preserved ejection fraction, pulmonary hypertension, atrial fibrillation, and heart valve disease. The present review summarizes the current knowledge on MR activation and antagonism in cardiovascular disease.