In general, stroke is the second leading cause of mortality and a leading cause of morbidity. The most common type is thrombotic which responsible for 65-85%. Treatments that are approved by guidelines include supportive care in an emergency unit, and reperfusion through use of intravenous recombinant-tissue plasminogen activator (r-tPA), intra-arterial fibrinolysis and mechanical thrombectomy. A prospective study carried out in two years enrolled patients with acute ischemic stroke who have done CT angiography of cerebral circulation to assessment of the collateral arterial state. A total number of 50 patients (25 males and 25 females). The main age was 53.7±11.56 years. Each patient was neurologically and clinically evaluated, underwent NCCT followed by CT cerebral angiography to assess large vessel occlusion, collateral circulation status according to Tan scale (0-3). Good state of the cerebral collaterals in patients with AIS was associated with good clinical outcome, good reperfusion, symptomatic ICH rate is low, mortality rate decline and stroke severity be less.