We developed a comprehensive individualized preventive care reminder system and then tested the hypothesis that directly involving patients in the reminder process would lead to greater use of preventive services than involving physicians only. There were three experimental groups of 350 patients each: in group 1 physicians and patients received the reminder; in group 2 physicians only received the reminder; in group 3 neither physicians nor patients received the reminder. Nine preventive care services were studied: blood pressure measurement; dental exam; ocular pressure measurement; stool exam for occult blood; influenza, pneumococcal, and tetanus vaccinations; mammography; and Papanicolaou smears. Need for these services was determined by telephone interview and chart review. To determine whether services were obtained, charts were reviewed after four to eight months of follow-up. For overall compliance with preventive recommendations and for several individual services (stool exam for occult blood, tetanus vaccination, mammography), group 1 patients received significantly more preventive care than group 2. Likewise, group 2 patients received more preventive care than group 3. These data show that involving patients in reminder efforts is an effective means of raising the level of preventive services.