To assess the usage, knowledge and attitudes of Patients Living with HIV with respect to supplements. A questionnaire was mailed to people living with HIV via HIV/AIDS organizations in Ontario and distributed to those attending the HIV-clinic of the University Health Network. The survey was completed by 312 subjects (95 female, 207 male). Self-rated health status was considered fair/good in 77.5% and excellent in 15.4% of participants. Vitamin/mineral supplement was used by 75.6%. Main reasons to take supplements were to: prolong life (56.1%); treat HIV-related conditions (19.9%); increase energy level (42.6%) and to boost immunity (36.5%). Among participants, 54.2% were somewhat familiar with supplements, 44.7% trusted the information on the labels and 28.2% felt that if a supplement is available for sale, it is safe. Supplements were mostly purchased at pharmacies (45.5%) and health food stores (30.1%). Only 25.9% and 27.9% of participants discussed their use of supplements with their HIV or family doctor respectively. Supplements are frequently used by people living with HIV without consulting their doctors. Current research has not shown a clear benefit from micronutrient supplementation and with the possible potential drug interactions, people living with HIV will need nutrition education regarding supplement usage and should report their use to their physicians.