The 1992 IMIA Yearbook of Medical Informatics reflects the worldwide research and development in medicine and health care where computers play an essential role. Most of today' s hospitals and practices are equipped with computers for the support of patient care, administration, and data communication. The development of such systems is based on extensive experience, obtained only after several generations of people and systems. A substantial part of the development of these systems can still be considered an art; the science required for such developmentis continuously expanding in size and importance.