The national Library of Medicine celebrated its sesquicentennial in 1986. The Library has played an important role in medical communication in this country for most of the 150 years since its founding. In the last 20 years, especially, the NLM's responsibilities have been expanded to include a variety of nontraditional library activities. Many of these new activities are based on computer and communications technology. Research now going on in the Library's Lister Hill Center shows promise of greatly altering the way future scientists and health practitioners have access to biomedical information.