Metoprolol is a selective beta(1)-adrenergic antagonist extensively used since 1975. Metoprolol has proven its efficacy in reducing cardiovascular events and mortality in patients with hypertension and coronary heart disease. A recently developed controlled release/ extended-release 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. A 100-mg metoprolol controlled/extended-release tablet contains 95 mg of metoprolol succinate and is considered to have equivalent activity of 100 mg metoprolol tartrate. After ingestion, the tablet disintegrates into individual pellets and each pellet acts as a diffusion cell releasing the drug at a relatively constant rate over a period of approximately 20 hours. The aim of this review was to determine the pharmacokinetic and pharmacodynamic properties of metoprolol succinate and to apply those properties in combination with other drugs mainly diuretics in the treatment of hypertension.