Cerebral ischaemia is a dynamic process affecting the cerebral parenchyma, with transient or permanent clinical symptoms, of varying duration and severity, and which is due to the occlusion of an artery in most cases. The clinical characteristics of cerebral ischaemia include sudden focal cerebral or ocular deficits, which may or may not resolve and have further clinical repercussions. On more rare occasions, ischaemia can be detected in an inadvertent fashion during a general or neurological check-up. In 80% of cases, the anterior (carotid) arterial system is affected, while in the remaining 20%, the posterior (vertebrobasilar) system is involved. Cerebral ischaemia is a medical emergency requiring prompt management and a thorough understanding of clinical semiology as soon as acute manifestations appear. The detection and prediction of cerebral ischaemia will be facilitated through the use of novel neuroimaging techniques, aiding therapeutic decision-making.