Recent studies have documented that physician compliance with recommended periodic health screening improves with reminders to physicians. These reminders, however, are often costly to maintain and modify. This study investigates the influence of a microcomputer tickler system on the ordering of mammograms. All women (N = 1262) aged 40 years and older who made visits to an outpatient office during a 6-month period were randomly assigned to one of two groups. For the experimental group, the date of the last mammogram ordered and recorded in the clinical database was printed on the encounter form generated for each patient visit. No information regarding previous mammograms was printed for patients in the control group. Women in the experimental group were more likely to have a mammogram ordered during the study period (19% compared with 12%, P = .001) and, as a result, were more likely to be in compliance with mammography guidelines at the study's completion (27% compared with 21%, P = .011). Microcomputerized data storage and retrieval systems may help increase physicians' attention to preventive health screening recommendations.