These 28 papers are launched by the European Telematics Applications Project HANSA (Healthcare Advanced Networked System Architecture), with support of the GMDS WG Hospital Information Systems and the GMDS FA Medical Informatics. They deal with architectural concepts, models and developments for hospital information systems. The HANSA project is based upon the European Prestandard for Healthcare Information System Architecture which has been drawn up by CEN/TC 251 PT01-13. The editors feel that this standard will have a major impact on future developments for hospital information systems, therefore the standard is included as an appendix.