Knowledge transfer in medicine has traditionally been achieved through personal communication, the medical literature, conferences and continuous medical education. However, many of these methods of communication have the problem of currentness, and the latest knowledge is mostly transferred with a certain delay. In particular, chronic disease management is frequently burdened by missing, incomplete or delayed communication. We present the implementation of a novel, Internet-based information system (RheumaNet) to facilitate rapid communication and information transfer between the 21 German Multipurpose Arthritis Centres (MACs). Medical information, agendas, urgent notifications, guidelines, etc., can be exchanged easily via electronic mail, file transfer protocol or the World Wide Web. RheumaNet allows interactive on-line communication as a common platform for joint projects or remote consultation. It supports a set of 'core documentation' that has been used by all German MACs for several years. RheumaNet was used for the organization, on-line presentation and evaluation of the 1997 annual meeting of the German Rheumatology Society and is currently appointed to establish its public representation in the 'Web'. An on-line version of the 'Quality Assurance Textbook' of German rheumatology is achieved with database-derived 'dynamic' Web pages, allowing easy access to any information within it. Advances in the future include the development of on-line patient information bulletin boards, on-line questionnaires, the coordination of rehabilitation and educational tools for medical students, and professional training.