The Hepatitis Knowledge Base is a prototype computerized information-transfer system aimed at supporting the health practitioner's day-to-day diagnosis, prognosis, and treatment decisions concerned with viral hepatitis. An overview of information-transfer problems in biomedicine is presented and issues pertinent to the knowledge-base concept are discussed. The following research activities are described: selection and organization of the content of the initial draft of the complete Hepatitis Knowledge Base; the method for consensus development by a nationally distributed panel of collaborating experts on the subject matter; methods for updating the knowledge base and maintaining its currency over time; use of a computer conferencing network as the principal medium of communication among the geographically dispersed experts and the project staff; support of on-line access to the knowledge-base contents; and formative evaluation of the above methods and limited field testing of the access system.