Cerebrovascular diseases are medical emergencies. Hospital admission rates for stroke vary from 40 to 80% depending on the country. The burden of stroke in terms of hospital expenditures and health costs is considerable. The necessity of admission to hospital and to acute stroke units (ASUs) in this population is a matter of debate. ASUs probably do not reduce the mortality rate, but they decrease the rate of complications, the level of disability, and perhaps the length of hospital stays. Aside from these efficiency criteria, ASUs may have other advantages for patient management, for the motivation of health professionals in cerebrovascular diseases and in teaching and research.