To conduct this research project, an IBD specialist who is a member of GETECCU has been selected from each Autonomous Community, who will act as the coordinator in their region. Gastroenterologists in charge of IBD Units in Spain will be contacted, or if unavailable, a gastroenterologist from each of the hospitals included in the National Catalog of Hospitals as of 31 December 2014 at http://www.msssi.gob.es/ciudadanos/prestaciones/centrosServiciosSNS/hospitales/ home.htm (last accessed 13 August 2015). The most appropriate strategy for identification of cases will be planned on a case by case basis in each Autonomous Community, according to the specific characteristics of this Community, each province and health area, with the aim of detecting all incident cases. The databases of the endoscopy units and pathology departments will be reviewed in all sites participating in the study during the year of enrollment, in order to detect any possible incident cases of IBD that not might not have been identified initially.