Esmolol is a unique cardioselective, intravenous, ultra-short acting, beta-adrenergic blocking agent. A 9-minute half-life with rapid clinical onset and offset of action and the ability to titrate the drug to changing circumstances makes esmolol a useful addition to our treatment armamentarium. The efficacy and safety of esmolol have been shown in specific clinical settings, i.e. in patients with unstable angina, myocardial infarction, atrial fibrillation or flutter and supraventricular tachycardia. In the emergency management of hypertension, tachycardia or arrhythmia in critical care units, emergency room and surgery, esmolol is effective by attenuating hemodynamic responses from sympathetic activation or endogenous catecholamine release. With careful titration and monitoring of the patient, esmolol is relatively safe in the management of hypertension or tachyarrhythmias associated with congestive heart failure or chronic obstructive lung disease where beta-blockers are otherwise contraindicated. Different dosage schedules have been employed as per the clinical setting and the diagnosis. Generally, esmolol is infused intravenously in doses ranging from 25-300 micrograms/kg/min, along with a loading dose or bolus. The most frequently reported adverse effect associated with esmolol infusion was hypotension. Adverse effects due to beta-blockade can be corrected by down-titrating or discontinuing the infusion with complete disappearance of clinical effects in 20-30 minutes. Therefore, as an ultra-short acting beta-blocker, esmolol is an important therapeutic option in the acute clinical setting.