Abstract
The diagnostic process can be described as a continuous interaction between doctor and layman, whether neither computers nor tests represent final solutions. In this process, exchange and comparison of disease concepts and their components take place. The situation is analysed from the viewpoints of clinical work and epidemiology in the case of the rheumatic diseases, especially rheumatoid arthritis. The layman's part in the diagnostic process is considerable, both in terms of quantity and quality. It is concluded that our knowledge is strikingly limited and that future study should be devoted to doctor and patient as a unit when they together create diagnosis. Furthermore, international comparability of results and measurement of health levels require an expansion of our knowlege of the diagnostic process.