OBJECTIVES: The objectives of this study were to identify the prevalence of the use of vitamin/mineral supplements or natural/herbal remedies, concurrent use of pharmaceutical medication, and to profile those most likely to use these complementary and alternative medicines (CAM) in the treatment of five chronic conditions identified as national health priorities (asthma, diabetes, arthritis, osteoporosis, heart or circulatory condition) within the Australian adult population. METHODS: Analysis of the Australian National Health Survey database, 2004-05. RESULTS: Approximately 24% (1.3 million) of Australian adults with a chronic condition regularly applied CAM to treatment. CAM was most often used exclusively or in combination with pharmaceutical medicine in the treatment of arthritis and osteoporosis. Fewer than 10% of adults with asthma, diabetes or a heart or circulatory condition used CAM, most preferring pharmaceutical medicine. Regular CAM users were more likely to be aged ≥60, female, have a secondary school education and live in households with lower incomes than non-users. Non-users were more likely to be 30-59 years old and tertiary educated. CONCLUSION AND IMPLICATIONS: Arthritis, osteoporosis and, to a lesser extent, heart or circulatory conditions are illnesses for which doctors should advise, and patients need to be most aware about the full effects of CAM and possible interactive effects with prescribed medicine. They are also conditions for which research into the interactive effects of CAM and pharmaceutical medication would seem of most immediate benefit.