The neurotransmitter/hormone adrenaline (epinephrine, adrenalin) plays a central role in the mammalian stress response, increasing heart rate, raising blood pressure, and increasing blood glucose levels. Adrenaline activates both alpha-adrenergic receptors and beta-adrenergic receptors. There are mainly three subtypes of beta adrenergic receptors known, beta1, beta2, and beta3. These receptors are expressed primarily in the heart, respiratory tissue, and adipose tissue. Beta3-receptors are abundant in brown adipocytes and play vital roles in lipolysis and thermoregulation. Beta adrenergic receptors are gaining much interest among researches in the studies of type-2 diabetes mellitus and obesity. It is also being considered as a therapeutic target for heart failure.