Because of the extent of the medical literature and the wide-ranging interests of medical scientists, it is not feasible today for a hospital library to provide from its own shelves all of the books and journals that are requested by its doctor clientele. The suggested alternative is for the hospital library to select an appropriate medical research library to serve as its reservoir library and to develop a realistic plan for using its collections to supplement its own smaller, working collection. A realistic plan embodies a clear understanding with the reservoir library and a contractual relationship that provides payment for services received. An important part of the plan is a clearly stated policy defining the level and quality of service to be expected from the reservoir library. An essential ingredient is a feasible system for overcoming the inconveniences and delays which tend to be imposed by the distance between hospital library and reservoir; certain devices are suggested for overcoming the distance barrier.