The chapter comprises of Beta-blockers (BBs) which were originally conceived and developed by Sir James Black to treat angina by reducing myocardial oxygen demand by view of their antiadrenergic action. The basic pathology of myocardial ischemia is a mismatch of myocardial oxygen demand and oxygen supply. BBs are effective in coronary artery disease owing to the fact that Reduction in heart rate, myocardial contractility and systolic blood pressure leads to decreased myocardial oxygen demand, Prolongation of diastole due to a reduction in heart rate improves coronary perfusion, antiarrhythmic effect, Improved myocardial energetics by inhibiting catecholamine-induced release of free-fatty acid from adipose tissue and reduce myocardial oxidative stress. The chapter mentions on beta-blockers in acute coronary syndrome: ST-segment elevation in myocardial infarction. Finally the chapter concludes with low-risk patients who benefit the least from BB therapy, and thus it is reasonable for continued treatment of patients with BB for more than 1 year post-MI, particularly in low-risk patients or those with preserved left ventricular ejection fraction.