The American sociologist Angelo Alonzo has put down the premises for a theory of illness behaviour based on an interactionist-situational framework. In this article I suggest that a disease concept of 'situational disease' based on this framework would be well suited for clinical work in general practice. The outlines of the theory is given and compared with a more traditional diagnostic model, especially with regard to consequences for treatment and research methods. I argue that there is a narrow relationship of disease models and research methodology and that e.g. a rigorous enforcement of the prevailing methodology of controlled clinical trials is liable to uphold an anachronistic disease model. Practice guidelines which originate from a situational understanding of disease should be encouraged and to this end general practice needs to develop a broad range of research methods suited to its distinctive professional role.