The advent of shared care coupled with the proliferation of heterogeneous distributed systems containing patient data have resulted in an urgent need to provide seamless integration of distributed electronic patient records. This paper presents the approach to this problem, which is being developed as part of a major EU Health Telematics project, SynEx. The approach is based on a core XML DTD corresponding to a flexible common model of the shared - or federated - Electronic Healthcare Record. Using this DTD, SynEx has successfully demonstrated the exchange of records between two heterogeneous and geographically separated sites.