After a short historical review and having dwelled on the nomenclature and legislative framework, the authors describe the medicolegal implications of the day hospital. They describe international experience within the various disciplines, with reference to economic aspects in terms of costs and the increased efficacy of these structures, the quality of service and government policies, in particular in industrialised countries. The authors conclude that day hospitals present considerable advantages both in economic terms and for patients. However, the organisation of the system needs to be improved and, where possible, procedures standardised. Bearing in mind the importance of costs to modern medicine, it is impossible not to take economic aspects into account, while also improving the quality of relations between doctors, patients and the health system.