PAOD represents a major challenge; which is rapidly growing due to increase in elderly population, in whom the peripheral vascular insufficiency increases. The standard line of treatment for this population was the surgical intervention, which may be associated with increased morbidity and mortality rates. As it is well known, traditional surgical revascularization is associated with reperfusion syndrome, which may result in multiorgan failure. The gradual way in which thrombolysis re-establishes the flow, allows the metabolites to be mobilized over time and allows the systemic effects of reperfusion injury to be easily tolerated.In addition, patients with small vessel occlusion are poor candidates for surgery. The intravascular administration of thrombolytic therapy originated in 1960 with i.v. treatment of pulmonary embolism.The thrombolysis by means of selective vascular infusion for occlusion entered the main stream in 1970. Since then, techniques for thrombolysis had advanced & branched in several directions. The three commonly used thrombolytic agents are SK, UK, t-PA. There are several studies comparing the efficacy of these agents & their outcome & compare them to the operative revascularization in acute thrombotic arterial occlusion. These studies agreed on difficulty to determine a standard dose of these agents & adopted different techniques of infusion. Review of different studies dealing with thrombolysis shows that any conclusion regarding the superiority of one lytic agent over another is limited by the lack of uniform definitions, use of reporting standards, dosing regimens, & techniques used in literature. As reviewed from the literature; t-PA is more effective lytic agent compared to UK, however it is associated with more bleeding complications.