Abstract. Clinical research significantly contributes to the better understanding of diseases and their treatment. Physicians, however, could not take fully advantage of the resulting scientific knowledge. To improve sharing and processing of primary clinical data new generation technologies for knowledge management are needed. In this paper we discuss some of their features on the basis of a real-world system in the domain Nephropathotology. We propose several interpretations of user-aware behavior and show how they influence the understanding and assessing of the similarity in CBR theory. Moreover, we illustrate our point with several examples, inspired by the experience, gained during the development of a CBR-based search engine within the scope of the OpEN.SC project.