OBJECTIVES: To determine preferences and marginal willingness to pay (MWTP) for osteoarthritis (OA) treatments, including complementary and alternative medicine (CAM) among a sample of Medicare beneficiaries 65+. METHODS: A discrete choice conjoint analysis was conducted with 181 participants recruited from 4 senior centers and one internal medicine practice in Memphis, TN. Data were collected via computer survey, and analyzed using Sawtooth Software according to covariates of age, race, gender, income, education, disability status, and OA duration.  Utility data and MWTP were derived from multinomial logit analysis. This study was conducted in accordance with ISPOR's Checklist for Good Research Practices in Conjoint Analysis.  RESULTS: Prescription pain (.35) and over-the-counter medications (.34) had the highest utility and physical therapy (-.72) had the lowest utility among conventional treatments. The most preferred CAM therapy was prayer/spiritual healing with a utility value of .71. The highest utility value for combination therapy was prescription pain medication and acupuncture (.42). The price attribute followed the expected trend as lower prices were associated with higher utility. This sample was willing to pay five dollars more for prayer/spiritual healing and was willing to pay nine dollars less for a combination of physical therapy and chiropractic than the referent (a combination of prescription OA medication and herbal/mineral supplements). CONCLUSIONS: This sample has significant preference for CAM in addition to conventional treatments.  These data suggest that healthcare providers should involve patients in treatment decisions to optimize treatment acceptance and compliance. Although the data show that prayer/spiritual healing is a valued therapy, it is not the only treatment preferred.  This result may reflect a desire for a more holistic view of healthcare. As options for CAM alone and in conjunction with conventional medications become increasingly available, the relationship between preferences illustrated by this study and health outcomes is important to examine.