Hospital libraries are special medical libraries located in health institutions (hospitals and university hospitals) or biomedical institutes. The group of medical libraries also comprises academic biomedical libraries affiliated with higher-education institutions in the field of biomedicine. At present, there are 28 special medical libraries and 8 academic biomedical libraries in Croatia. The author refers to collections and users of hospital libraries, and gives examples from daily practice that clearly show the need for a well-organized research and development center at both the local and national level. Among other reasons, such a research and development center is necessary due to the following: stocktaking and "writing off" of library items, organization of depositary library for older print collections, collection of data for union catalog(s) at the national level, networking and integrated information library system, continuous postgraduate education of librarians, position of librarians in health institutions, updating of standards for special libraries, etc. The requirements of hospital libraries with regard to research and development center are similar to those expressed by academic libraries in the field of biomedicine. The National and University Library in Zagreb should take care of research and development at the first (national) level, whereas at the second (regional) level this task should be fulfilled by university Iibraries (for the region of the Zagreb University, the National and University Library should fulfill this task at both levels). In other words, research and development center for special libraries should be organized in accordance to the Article 18 of the Regulations on Research and Development of Libraries in Croatia and the Article 31 of the Act on Libraries.