3 groups of elderly people (65–80 years) were studied as regards their serum 25-hydroxyvitamin D (25-OH-D) concentrations, their dietary vitamin D intake and sunlight exposure during 1 year: group 1 (long-stay geriatric patients); group 2 (residents at an old people’s home), and group 3 (elderly people living in their own homes). Young adults (30–50 years) served as controls. The 25-OH-D concentration in group 1 was significantly lower during the whole year than in any other group and the concentration in group 2 was significantly lower than in group 3 and the controls. The low 25-OH-D level in the long-stay geriatric patients and in the residents at the old people’s home is a consequence of both a low dietary vitamin D intake and a low exposure to s