Thrombolysis has become an approved therapy for acute stroke. However, many stroke patients do not benefit from such treatment, since the presently used criteria are very restrictive, notably with respect to the accepted time window. Even so, a significant rate of intracranial hemorrhage still occurs. Conventional cerebral computed tomography (CT) without contrast has been proposed as a selection tool for acute stroke patients. Recently, more modern magnetic resonance imaging (MRI) and CT techniques, referred to as diffusion- and perfusion-weighted imaging, and perfusion-CT, have been introduced. They afford a comprehensive noninvasive survey of acute stroke patients as soon as their emergency admission, with accurate demonstration of the site of arterial occlusion and its hemodynamic and pathophysiological repercussions of the brain parenchyma. The objective of this review article is to present the advantages and drawbacks of CT, using iodinated contrast, and MRI, using gadolinium, in the evaluation of acute stroke patients.