Abstract: Objective: To study non-vitamin, non-mineral (NVNM) supplements use and disclosure of among hospitalized internal medicine patients.Methods: A convenience sample of patients completed an interviewer-administered questionnaire examining use of and perceptions regarding NVNM supplements, and disclosure to medical personnel.Results: 280 patients were interviewed (54% female), 15.4% reporting NVNM supplement use. This practice was more prevalent among female patients (p=0.045), more educated (p<0.001) and patients with more impaired quality-of-life, measured by the SF-12 tool (p<0.020). The most common factor influencing NVNM supplement use was a physician’s recommendation. Most (74%) patients using NVNM supplements reported having disclosed this practice to community-based physicians, with only 23.7% disclosing to hospital staff. Six patients reported using supplements at the exclusion of conventional medication, with potentially serious implications.Conclusion: While the majority of patients using NVNM supplements are sharing this information with their primary-care physicians, there is little disclosure of this practice to hospital staff. This may be due to a perceived negative attitude of medical professionals to complementary medicine, and a lack of awareness by hospital staff regarding such practices.Practice implications: Hospital-based medical professionals need to be aware of the use of NVNM supplements and the resulting implications by their internal medicine patients.