Objectives: The purpose of this study was to determine if participant diagnosis, as determined by a health care provider, is associated with dietary supplement (DS) use. Design/setting: Surveys from 1255 study participants aged 34-84, part of the Midlife in the US Study (MIDUS 2 Survey) Biomarker Project, were reviewed. Participant data included pharmaceutical use (prescription and overthe-counter medications (OTC)), clinical symptoms and diagnosis, and laboratory results. Associations were calculated between the above participant characteristics and DS use. Main outcome measures: Frequency of DS use for physician-reported diagnoses. Results: Overall prevalence of DS use was 32.4%. Participants taking DS were more often female (p = .048), white (p < 0.001), and older (mean age 57 years, p < 0.001). Participants taking DS reported taking more OTC (p < .001) and prescription medications (p=.024), and had an increased number of chronic conditions (p = .004). Participants reporting physician-diagnosed diabetes were significantly less likely to be taking DS (p = .0066), while participants with eye disease (p = .001), high cholesterol (p = 0.041), cancer (p = 0.042), and arthritis (p = 0.044) were more likely to be taking DS than those without those conditions. No difference in DS use was found between patients with and without other identified medical conditions. After adjusting for age, race/ethnicity, and gender, only diabetes remained a significant predictor of decreased DS use (OR 0.588, CI 0.388-0.873, p = .01).