This paper contributes to the discussion of R. Haux paper on essential aims and tasks of medical informatics. New views on structure of informatics and consequently medical informatics are given. Information is introduced as outside and inside information. Inside information is divided into three different types as data, evidence and knowledge. This terminology slightly differs from the commonly used terminology data, information and knowledge. Based on understanding of information as outside and inside information the field of informatics is divided into four rings, namely Information Basic Ring, Information Methodology Ring, Information Interface Ring and Information Technology Ring. Medical informatics is defined and its structure explained using four information rings. These views on informatics and medical informatics open possibilities to see more clearly where are the essential aims and tasks of medical informatics. (C) 1997 Elsevier Science Ireland Ltd.