This study was launched to address concerns about the needs of after-hours users going unmet at the Cleveland (Ohio) Clinic Foundation Library Services Department. The collection itself is available for use on the premises by clinic employees 24 hours a day, but employees do not remain on site to provide assistance, materials may not be signed out after hours, and no online searching or library catalog searches may be done. The study consisted of distributing a questionnaire exclusively to 113 after-hours users of the library, and the responses (n=54) showed that overnight use of the premises is not casual, but purposeful and essential; 1 in 10 after-hours patrons make use of the library to answer questions regarding emergency or critical care. Other after-hours reasons for being in the library are represented in the data as well, like article pickup, access to a photocopier, or desire for a quiet area. More than any other desires for services, user responses called for expanded library hours and more continuous access to online databases. A followup study is recommended which would query a more representative sample of all patrons and solicit their insights into the efficacy of the present after-hours system and the dilemmas of providing services without benefit of staff. Six tables and three figures illustrate the results. (Author/BEW)