The integration and evolution of existing systems represents one of the most urgent priorities of healthcare information systems in order to allow the whole organisation to meet the increasing clinical organisational and managerial needs. This paper discusses how an open architecture, based on the introduction of a middleware of common healthcare-specific services not only reduces the effort necessary for allowing existing systems to interwork, but also automatically establishes a functional and information basis common to the whole organisation, on top of which also new applications can be rapidly developed, natively integrated with the rest of the system.

Such architecture has been already formalised through the proposed European preStandard, defined by the CEN/TC251/PT1-013 “Standard Architecture for Healthcare Information Systems” [1].

Through the utilisation of the DHE middleware, the effectiveness and validity of this approach is also being demonstrated in practice by several hospitals and healthcare industries from 13 European countries, which collaborate in the Hansa project, presently running under the Telematics Application Programme of the Commission of the European Communities.