Brain Computed tomography (CT) scan has been used in the past to exclude a hemorrhagic stroke, to determine a possible cause of the stroke patient symptoms, and to demonstrate a stabilized area of hypoperfusional flow. Several results from CT scan studies suggested that we could have new information on prognosis and outcome, localization, and risk of infarction. In this view, CT scan in acute stroke may contribute, using objective measures, to evaluate the inclusion in clinical and therapeutical trials, such as thrombolytic therapy. The lack of consensus among clinicians does not allow a secure and definitive system of CT scan evaluation. Besides its common uses, more recently brain CT scan provides new techniques utilizing advanced algorithms of reconstruction, with promising properties not yet completely verified, to highlight more aspects of acute stroke in the early phase. Despite this limitation, progress on neuroradiological techniques reinforces the concept that brain CT scan remains the key of studies, as well as of validation and routine treatment in terms of feasibility, low cost, and widely availability.