Stroke is a medical emergency that is common and severe. Its diagnosis is based on questioning of the patient or those around him and on clinical examination. Stroke requires rapid investigation by imagery of the brain and intra- and extracranial vessels. Currently these investigations associate CT scan of the brain (which differentiates infarcts and haemorrhage) and cervical and intracranial ultrasound examination, or angiography if vascular malformation is suspected. Magnetic resonance imaging, when available for emergency use, is greatly superior in its earlier detection of signal abnormalities, its diagnostic precision and visualisation of the vessels. Recent clinical trials have shown the effectiveness of stroke management in specialised units (30% reduction in the number of deaths or institutionalised patients) and of very early intravenous administration of rt-PA (within less than 3 hours). Thus, neurovascular emergency treatment centres should be rapidly established, as has been done in cardiology for emergency care of myocardial infarcts.