In spite of the current preoccupation with problems of ILL/DDS (interlibrary loan/document delivery service), little national level data exists on the characteristics of materials users seek through ILL/DDS. The library profession speculates and argues about the role of the library in the future of ILL/DDS in the absence of data on what users now request through ILL/DDS. This study describes publications requested through OCLC PRISM Interlibrary Loan. The survey findings are based on over 100,000 requests: 56% were for monographs; 43% were for serials. More than 40% of monograph requests were for materials published 10 years ago or earlier. Sixty percent (60%) of the monographs requested were held by 11 to 300 libraries. ILL requests were sorted by LC classification. The fields of science, medicine, and social science appear to draw more from serial literature than do other subject fields. In other subject fields, serials and monographs seem to be, more or less, in equal demand.