The University Hospitals of Geneva (HUG) are the result of the merge of six hospitals into one single organization. While a true fusion of the management has been effectively done, it was not the case five years after for several databases, and in particular the ADT (Admission, Discharge, Transfer). In order to truly realize the fusion, a new ADT service has been built using state of the art technology and standards in order to replace the existing seven services. This paper presents the results of the redesign and development of the new ADT service. The data model, based on HL-7 RIM, is described and the technologies selected are presented. Finally, a status after a few months of production is presented.