BACKGROUND: Very little is known about herbal and dietary supplement disclosure in adults with chronic medical conditions, especially on a national level. OBJECTIVE: To examine herbal and dietary supplement disclosure to conventional health care providers by adults with chronic medical conditions. DESIGN: Data on herbal and dietary supplement use (N = 5456 users) in the previous year were used from the 2002 National Health Interview Survey. Bi-variable analyses compared characteristics between herbal and dietary supplement disclosers and nondisclosers. Multivariable logistic regression identified independent correlates of herbal and dietary supplement disclosure. RESULTS: Overall, only 33% of herbal and dietary supplement users reported disclosing use of herbal and dietary supplements to their conventional health care provider. Among herbal and dietary supplement users with chronic conditions, less than 51% disclosed use to their conventional health care provider. Hispanic (adjusted odds ratio and 95% confidence interval = 0.70 [0.52, 0.94]) and Asian American (adjusted odds ratio and 95% confidence interval = 0.54 [0.33, 0.89]) adults were much less likely than non-Hispanic white Americans to disclose herbal and dietary supplement use. Having less than a high school education (adjusted odds ratio and 95% confidence interval = 0.61 [0.45, 0.82]) and not having insurance (adjusted odds ratio and 95% confidence interval = 0.77 [0.59, 1.00]) were associated with being less likely to disclose herbal and dietary supplement use. CONCLUSION: Herbal and dietary supplement disclosure rates are low, even among adults with chronic conditions. These findings raise concerns about the safety of herbal and dietary supplements in combination with allopathic care. Future studies should focus on educating physicians about crosscultural care as well as eliciting information about herbal and dietary supplement use.