Medical informatics attempts to provide the theoretic and scientific basis for the use of automated information systems in biomedicine. Even though a new field, its roots are in the 19th century. The National Library of Medicine (NLM) began classifying the medical literature and publishing the Index Medicus in 1897; in the early 1960s, the growth of the index gave rise to MEDLARS, the first successful, large-scale, computerized bibliographic system. In 1971, about the time MEDLARS evolved into a nationwide on-line retrieval system known as MEDLINE, a committee of the Association of American Medical Colleges published a report calling for the NLM to exert strong leadership in developing computer applications for information transfer in medicine. The NLM has sponsored several training and research programs in this area and is now developing the concept of "centers of excellence" in medical informatics. In addition, there are a number of current research and development activities within the NLM internal and extramural programs that may influence the progress of medical informatics.