SignIn-Stat, a PC-based, menu-driven program, collects information from users of the library's public access computer systems. It was used to collect patron use data for the library's four CD-ROM workstations for the period September 1987 to April 1988 and to survey users for the period December 1987 to March 1988. During the sample period, 5,909 CD-ROM uses were recorded. MEDLINE was the most heavily used database, followed by PsycLIT and Micromedex CCIS. Students accounted for 61% of the use, while faculty, residents, and staff were responsible for 31%. Graduate students had the highest rate of use per student. Nineteen percent of use was by patrons who had never used CD-ROMs before, while 37% was by patrons who had used CD-ROMs ten or more times. Residents were the least experienced user group, while graduate students and faculty were the most experienced.