The realities of medical practice require that useful decision support systems must support a range of information management and decision making activities, and provide these services within a versatile and extensible package. The LEMMA project addresses important issues concerning the technical and practical feasibility of advanced systems for primary care and their possible deployment across EC member states. The Oxford System of Medicine aims to develop a comprehensive information management and decision support system for general practitioners, whilst other parts of LEMMA have investigated the applicability of the techniques in other medical fields, principally oncology. The project has illustrated how logic based technologies can be exploited and extended to achieve these goals, whilst studies of the potential for introducing acceptable medical decision support systems into the health care systems in a variety of countries have been uniformly encouraging.