Communication between medical experts and patients is considered from a psycholinguistic point of view. The paper briefly introduces our research program that is focussing on mutual knowledge assessment and adaptation in expert-layperson communication. Here, we focus especially on the overlapping of words between doctor and patient. Starting from research on lexical entrainment we developed a software tool that improve written communication between expert and layperson. The Concept Revision Tool (CRT) supports experts’ adaptation to laypersons by reflecting expert’s word use and fostering revision in order to gain patient-orientated explanations.