A significant number of Australians are deficient in vitamin D--it is a fallacy that Australians receive adequate vitamin D from casual exposure to sunlight. People at high risk of vitamin D deficiency include elderly people (particularly those in residential care), people with skin conditions where avoidance of sunlight is advised, those with dark skin (particularly if veiled), and those with malabsorption. Exposure of hands, face and arms to one-third of a minimal erythemal dose (MED) of sunlight (the amount that produces a faint redness of skin) most days is recommended for adequate endogenous vitamin D synthesis. However, deliberate sun exposure between 10:00 and 14:00 in summer (11:00-15:00 daylight saving time) is not advised. If this sun exposure is not possible, then a vitamin D supplement of at least 400 IU (10 microg) per day is recommended. In vitamin D deficiency, supplementation with 3000-5000 IU ergocalciferol per day (Ostelin [Boots]; 3-5 capsules per day) for 6-12 weeks is recommended. Larger-dose preparations of ergocalciferol or cholecalciferol are available in New Zealand, Asia and the United States and would be useful in Australia to treat moderate to severe vitamin D deficiency states in the elderly and those with poor absorption; one or two annual intramuscular doses of 300 000 IU of cholecalciferol have been shown to reverse vitamin D deficiency states.