The field of medical informatics in its current understanding is defined and criteria distinguishing this field from similar areas are provided. Special consideration is given to its position at a School of Medicine-in particular to the University of Vienna Medical School with the Vienna General Hospital as its teaching hospital. Demands for medical informatics and electronic data processing (EDP) in this extended field of activity come from four different sources: (1) research in medical informatics, (2) teaching of medical informatics as well as EDP training, (3) EDP service for research and teaching, and (4) EDP hospital operations to assist patient care. (Purely administrative EDP demands are not considered here.) It is shown that the different demands can be fulfilled by the usually available institutions involved in medical informatics and EDP at a School of Medicine. At many places these institutions are as follows: (1) a department or division of medical informatics with a possibly attached computer center dedicated to provide assistance in the area of research and teaching, (2) the computer center of the respective university the School of Medicine belongs to, (3) the computer center of the hospital-owned institution responsible for all EDP activities connected to patient care, and (4) external software companies and EDP training centers. To succeed in the development of an exhaustive, school-wide system of medical informatics and EDP that considers the different demands in research, teaching, and EDP hospital operations equally, close and well-suited coordination between the institutions involved is necessary.