The prevalence of vitamin D deficiency varies, with the groups at greatest risk including housebound, community-dwelling older and/or disabled people, those in residential care, dark-skinned people (particularly those modestly dressed), and other people who regularly avoid sun exposure or work indoors. Most adults are unlikely to obtain more than 5%-10% of their vitamin D requirement from dietary sources. The main source of vitamin D for people residing in Australia and New Zealand is exposure to sunlight. A serum 25-hydroxyvitamin D (25-OHD) level of ≥ 50 nmol/L at the end of winter (10-20 nmol/L higher at the end of summer, to allow for seasonal decrease) is required for optimal musculoskeletal health. Although it is likely that higher serum 25-OHD levels play a role in the prevention of some disease states, there is insufficient evidence from randomised controlled trials to recommend higher targets. For moderately fair-skinned people, a walk with arms exposed for 6-7 minutes mid morning or mid afternoon in summer, and with as much bare skin exposed as feasible for 7-40 minutes (depending on latitude) at noon in winter, on most days, is likely to be helpful in maintaining adequate vitamin D levels in the body. When sun exposure is minimal, vitamin D intake from dietary sources and supplementation of at least 600 IU (15 µg) per day for people aged ≤ 70 years and 800 IU (20 µg) per day for those aged > 70 years is recommended. People in high-risk groups may require higher doses. There is good evidence that vitamin D plus calcium supplementation effectively reduces fractures and falls in older men and women.