This article introduces the Bulletin's special issue devoted to international health sciences librarianship with a discussion of the formal structures of international cooperation. The International Federation of Library Associations and Institutions' (IFLA) Biological and Medical Sciences Libraries Section conducts activities along four strands: world and regional health sciences library directories, mutually supportive regional groupings, a quarterly newsletter, and the quinquennial International Congress on Medical Librarianship. These activities, as well as those of other organizations, make up the formal international structure of health sciences librarianship.