This volume contains the proceedings of the NATO Advanced Study Institute on "Picture Archiving and Communication Systems (PACS) in Medicine" held in Evian, France, October 14- 26, 1990. The program committee of the institute consisted of H.K. Huang (Director), Osman Ratib, Albert Bakker, and Gerd Witte. This institute brought together approximately 90 participants from 15 countries. These proceedings are the accumulation of eight years of research and development results in PACS by various dedicated groups throughout the world. The purpose of this institute was to review the most recent technology available for PACS and some clinical results. The readers should notice the remarkable advances in this field by comparing the contents in these proceedings with those in a previous institute on "Pictorial Information Systems in Medicine" held August 27 - September 7, 1984 in Braunlage/Harz, Federal Republic of Germany, and published as Vol. 19 in this series. The institute was organized according to four categories: PACS components and system integration, PACS and related research in various countries and manufacturing companies, clinical experience and research support, and participants' scientific communications. In PACS components, we included image acquisition, workstations, data storage and networking. In system integration, topics on interfaces between Hospital Information System (HIS), Radiology Information System (RIS) and PACS, clinical reports, the ACR/NEMA standard, databases, reliability, and system integration were discussed. This lecture series emphasized the technical detail and "how to" aspects.