This article begins with a description of a typical reserve collection in a foreign university library and the problems reserve librarians face in a print-based environment. It goes on to discuss how electronic reserve systems have emerged since 1991. Three electronic reserve systems: ACORN, ERes and INNOPAC electronic reserve module are described in detail to illustrate the research findings of some experimental projects. The experiences of a foreign reserve book room are quite different from those of our local libraries. The heavy usage rate and the inclusion of a high number of periodical articles are not seen in local reserve collections. That explains why electronic reserve projects have not yet emerged in Taiwan libraries.