The actual use of computer-based decision-support systems in routine practice has been disappointingly low. Although underlying reasons need to be studied, actual use is often a trailing indicator for success. One of the characteristics of our technological age seems to be that developments may take decades to mature followed by a rapid dissemination. In the area of computer-based patient records, for example, decades of research had little impact. In recent years, however, the Dutch general practitioners are rapidly introducing computer-based patient records in their practices. Although actual use may be a trailing indicator, paradigms underlying research in the area of computer-based decision support are changing. Two distinct lines of research seem to be emerging. First, those who develop systems for actual use increasingly focus on the environment and setting in which medical decisions are made. That is, the emphasis will shift from casting medical knowledge in some formalism to enabling physicians and other health-care professionals to deliver care, to communicate and to interact. In a second line of research, the notion of casting an individual's expertise in some formalism has been replaced by a focus on the nature of medical knowledge, and how to model that knowledge.