Within the next decade profound changes in the health care delivery systems are likely to occur, including continuous efforts at cost control and an increased emphasis on quality assurance and outcomes by health payers. There will be an increased reliance on evidence-based medicine, and an increased emphasis on decentralized and coordinated care through regional health care networks. There will be a need for guideline-driven, distributed decision support systems integrated with clinical information systems, and added value, regional health information networks, to enable implementation of the future health care programmes relying on wide dissemination and use of clinical practice guidelines. The theoretical and technical foundations for development of these systems already exist or are going to emerge from the ongoing R & D activities within AIM and other CEC programmes. Main issues to be addressed within the fourth Framework Programme include integration of guideline-driven Decision Support Systems with Clinical Information Systems into clinical Workstations, Tools for collaborative development, validation and maintenance of large clinical knowledge bases (KB), KB safety and soundness issues and development of the necessary infrastructure for regional or national health information networks.