Tourniquet is invaluable instrument to plastic, hand and orthopedic surgeon. It helps create a bloodless field for easy operation and reduces operative time. The advantages of tourniquet is no without its share of complication including nerve and skin injuries and devastating vascular lesions leading to amputation or death. A thorough understanding of the local and systemic effect of tourniquet is essential to minimize the complication. Various physical and pharmacological modifications reduce the reperfusion injury and also help increase tourniquet time. This review discusses the principle, physiology and complications of tourniquet. Keywords: Tourniquet, Limb occlusion pressure, Reperfusion injury, Nerve palsies, Limb protector sleeves.