In professional medical ethics, the physician traditionally is obliged to fulfil specific duties as well as to embody a responsible and trustworthy personality. In the public discussion, different concepts are suggested to describe the desired underlying attitude of physicians. In this article, one of them--empathy--is presented in an interpretation that is meant to depicture (together with the two additional concepts compassion and care) this attitude. Therefore empathy in the clinical context is defined as the adequate understanding of the inner processes of the patient concerning his health-related problems. Adequacy is scrutinized on behalf of the emotional and subjective involvement of he physician, and on the necessary dependence on medical-moral-goals. In the present interpretation, empathy alone is no guarantee of the right moral attitude, but a necessary instrumental skill in order to perceive and treat a patient as an individual person. The concepts of compassion and care that will be discussed in two forthcoming articles are necessary parts to describe the desired moral attitude of the physician more completely.