This Review focuses on the application of telemedicine to the care of patients with acute stroke (telestroke), from the prehospital setting through hospitalization. Telestroke has grown remarkably in the past decade and has entered mainstream care for patients with acute stroke. Telestroke enables such patients to be remotely evaluated, thereby allowing optimal treatment and management even in clinically underserved areas and removing geographical disparities in access to expert care. Telestroke systems enable thrombolytic treatment to be administered in community and rural hospitals, and facilitate the appropriate transfer of patients with complex conditions (who require critical care services and neurosurgical or intra-arterial interventions) to a comprehensive stroke centre. Decision-analytic models show that telestroke is cost-effective from both a societal and a hospital perspective. Limitations to the use of telestroke in the USA include the need for state licensing and credentialling of physicians, and the technical requirements of a minimum network bandwidth (which is still lacking in some regions). However, the opportunity exists for telestroke to become the backbone of an electronic stroke unit and to be used to identify and enrol patients in clinical trials of acute stroke treatment. The use of telestroke in the prehospital setting has been hampered by limited telecommunication availability, but these problems might be mitigated by fourth-generation cellular data networks.