Background and Purpose: The arterial endothelium plays a number of important roles in the maintenance of normal vascular function. Normal endothelial activities include control over thrombosis and thrombolysis, platelets and leucocytes interactions with the vessel wall and regulation of vascular tone and growth. Because endothelial dysfunction probably contributes to disease states such as hypertension and atherosclerosis, there has been widespread recent interest in testing endothelial dysfunction in vivo. In cerebral vasculature endothelin-1(ET-1) is thought to be involved in several pathological conditions including vasospasm following subarachenoid hemorrhage and stroke .Several noninvasive and minimally invasive techniques for measuring vascular function have been developed: ultrasound diameter measurements, laser Doppler fluxmetry in combination with local administration of vasoactive drugs through iontophoresis and plasma markers as plasma ET-1 level. The combination of these techniques makes it possible to study arterial stiffness, endothelial function and regulation of blood flow. Subjects and Method: The study included forty patients suffering of recent onset stroke (within the first week of the onset of the symptoms), divided into twenty patients with hemorrhagic stroke and another twenty patients with ischemic thrombotic stroke. Ten sex and age matched healthy subjects will be accepted as a control group. All participants will be subjected to the following : complete neurological examination, plasma triglyceride and cholesterol, plasma ET-1 level ,Brain CT without contrast, extracranial carotid Doppler study, transcranial carotid Doppler for the middle cerebral artery indices and laser Doppler study for skin microvascular reactivity. Conclusion: ET-1 is thought to be involved in several pathological conditions in the cerebral vasculature including vasospasm following subarachenoid hemorrhage and stroke and contributes to disease state such as hypertension and atherosclerosis in peripheral vascular bed.