Background: In cerebral ischemia there is an enhanced expression of matrixmetallo-proteinase-9 (MMP-9), which has been associated with variouscomplications including excitotoxicity, neuronal damage, apoptosis, blood–brain barrier (BBB) opening leading to cerebral edema, and hemorrhagictransformation.MMP-9 level is related to stroke severity and stroke outcome.MMP-9 also related to vascular remodeling and atherosclerosis. Objectives:The present study aimed to investigate possible relation between MMP-9 levelduring first 24 hours following ischemic stroke and after 1 month of follow upand blood brain barrier disruption, infarct size, stroke severity, hemorrhagictransformation and functional outcome after acute ischemic stroke. It alsoaimed to investigate the possible relation between MMP-9and carotid arteryatherosclerosis on duplex ultrasound in both patients of AIS and healthyindividuals. Subjects and methods: The present study was conducted on 30patients with acute ischemic stroke within 24 hours from onset of stroke and 30normal volunteers as control subjects. Level of functional impairment afterstroke in patients was assessed using the National Institute of Health strokescale (NIHSS) and the Modified Rankin Scale (mRS) within 24 hours afterstroke onset and after 1 month. Assessment of serum MMP-9 within 24 hoursafter stroke onset and after 1 month and CT scan and carotid artery duplex wereperformed to all patients. Control subjects were submitted to assessment ofserum MMP-9.and Carotid artery duplex. Results: There was statisticallyhighly significant positive correlation between serum MMP-9 level and IMT ofCCA on both sides among non-stroke control subjects and patients with acuteischemic stroke. There was statistically significant positive correlation betweenMMP-9 level on admission and size of infarction, stroke severity, hemorrhagictransformation of infarction.MMP-9 level also correlate with disabilityfollowing stroke. Conclusion: High MMP-9 level is associated with carotidatherosclerosis in both patients with ischemic stroke and non-stroke subjects.Higher MMP-9 level following acute ischemic stroke is correlated to severityof stroke, size of the infarction, risk of hemorrhagic transformation and pooroutcome after stroke.