The anesthetic use of α2 adrenergic agonists has been of considerable and sustained interest for the last fifteen years. They are nowadays familiar to many anesthetists due To their different sedative, hemodynamic and analgesic properties. The exact role of α2 agonists especially clonidine and dexmedetomidine remains a matter of debate and poorly defined despite considerable clinical evidences. The net effect of activation of α2 adrenergic receptors is modulation of sympathetic nervous system activity. Manifestations of thisresponse include decrease cardiac out put, heart rate and systemicvascular resistance, also reduction of blood pressure and systemicvasodilatation.