Metoprolol is a selective beta(1)-adrenergic antagonist extensively used in major fields of cardiology since 1975. Metoprolol has proven its efficacy in reducing cardiovascular events and mortality in patients with hypertension and coronary heart disease in large clinical trials. Recently developed controlled release/extended release (CR/XL) formulation of metoprolol succinate was designed to provide relatively constant metoprolol plasma concentrations and beta(1)-blockade while retaining the convenience of once daily administration. The avoidance of high peak plasma concentrations with metoprolol succinate is associated with lesser degree of adverse effects and may improve patients compliance. This formulation of metoprolol has demonstrated efficacy in reducing cardiovascular events and mortality in patients with heart failure. More recently evidence for antiatherogenic activity of metoprolol succinate has been also obtained.