Interoperability in data exchange has the potential to improve the care processes and decrease costs of the health care system. Many countries have related eHealth initiatives in preparation or already implemented. In this area, Switzerland has yet to catch up. Its health system is fragmented, because of the federated nature of cantons. It is thus more difficult to coordinate efforts between the existing healthcare actors. In the Medicoordination project a pragmatic approach was selected: integrating several partners in healthcare on a regional scale in French speaking Switzerland. In parallel with the Swiss eHealth strategy, currently being elaborated by the Swiss confederation, particularly medium-sized hospitals and general practitioners were targeted in Medicoordination to implement concrete scenarios of information exchange between hospitals and general practitioners with a high added value. In this paper we focus our attention on a prototype implementation of one chosen scenario: the discharge summary. Although simple in concept, exchanging release letters shows small, hidden difficulties due to the multi-partner nature of the project. The added value of such a prototype is potentially high and it is now important to show that interoperability can work in practice.