This opinion paper discusses the potentials of telemedicine in relation to the user needs as well as the challenges that are foreseen in medical informatics research and development. Given the developments in telecommunications (ie. the ENS) and the fact that Knowledge Based Systems (KBS) become integrated functionalities the perspective emerges of an open health care information system profiting from the access to a net of multiple KBS. Particular user needs in this respect are: I) means to assess the validity of the KBS applications, 2) features for getting access to more than one KBS when seeking advice, ie. a Decision Support System (DSS) functionality, and 3) a generic interfacing system towards knowledge based DSS. Subsequently the challenges for medical informatics are: 1) validity and applicability assessment, 2) transferability of medical data, information and knowledge, and 3) managing a bidding approach for seeking advice.