This paper describes the experience of an academic health sciences library which made BRS/After Dark, an end user search service, available to its clientele as a complement to its mediated search service. The library environment, initial publicity efforts and administrative procedures are discussed. An attempt is made to evaluate the usefulness of the service in a library environment. This evaluation, covering a three-month period, is based on the observations of the librarians administering the service and an exit interview conducted with searchers over a two-month period. User satisfaction, both observed and recorded, was quite high; however, the librarians found that users had more difficulty in constructing appropriate search strategies than had been anticipated. Overall, the service is assessed as highly useful.