This article updates a prior citation analysis of medical decision making, published in this journal in 1984. Building on the original core list, decision making papers were added based on any of three criteria: citation of three papers already on the list, identification by a MEDLINE search (CATLINE for books) as relevant to the topic, or mention in a recent review article on decision analysis. The revised core list contains 105 articles and five books. The changes in the field of medical decision making from 1978 to 1981 are reviewed, and key areas of development are identified by co-citation clustering.