OBJECTIVES: Although complementary and alternative medicine (CAM) use is becoming increasingly prevalent in the United States, knowledge regarding complementary and alternative therapy use in older adults is limited. The purposes of this study were to (1) assess the prevalence and patterns of CAM use in a probability-based sample of older adults; (2) describe the characteristics of older CAM users; and (3) identify factors associated with complementary and alternative medicine use/nonuse. METHODS: A cross-sectional survey design was used. An age-stratified sample of community-dwelling adults ages>or=65 (N=1200) was randomly selected from the Minnesota Driver's License/Identification Tape using names from the Twin Cities seven-county metropolitan area. The mailed questionnaire included items on demographics, health status, health care utilization, CAM modality use, reasons for use, costs, and complementary and alternative therapy use satisfaction. Descriptive statistics, chi-square tests, and regression analysis were performed. RESULTS: Overall, 62.9% (N=445) of the respondents reported use of one or more complementary and alternative medicine modalities with an average of three modalities (SD+/-1.9, range 1-11). The top five CAM modalities used were nutritional supplements (44.3%), spiritual healing/prayer (29.7%), megavitamins (28.3%), herbal supplements (20.7%), and chiropractic (17.8%). Maintaining health and treating a health condition were the primary reasons for CAM use. The most common conditions treated were arthritis (44.4%) and chronic pain (23.5%). Demographic variables were not significantly different between CAM users and nonusers. CAM users reported more unhealthy days than nonusers did. Overall satisfaction with CAM use was high (80%). Symptoms of a health problem and desire for personal control over health motivated CAM use. The main barriers to CAM use were lack of reason to use and knowledge about CAM. Only 53% of users disclosed CAM use to their primary care providers. CONCLUSIONS: CAM use is common in older adults, especially those with health problems. The widespread use of oral supplements combined with not disclosing CAM use to primary care providers is a concern.