Despite the proven benefits of thrombolysis for patients presenting with acute ischemic stroke, only a limited number of patients receive thrombolytic therapy. The reason for the low treatment rate is that thrombolysis is only effective a few hours after the onset of ischemic stroke, so delays in patients being admitted to hospital and being diagnosed mean that the therapeutic window is often missed. Major factors that lead to prehospital delay include the general public's lack of knowledge of stroke symptoms and their poor understanding of the appropriate course of action following a stroke. Indeed, the patients who arrive early in hospital tend to be those who recognize the symptoms of stroke and take them seriously. Deficiencies in the identification of stroke by emergency medical services and general practitioners also contribute to prehospital delay. Aggressive, combined educational programs aimed at the general public, general practitioners, and medical and paramedical hospital staff can lead to increased stroke treatment rates. In this Review, we explore the extent of prehospital delay in stroke, identify the factors that affect the time taken for patients to reach hospital, and describe strategies designed to reduce the delay.