Vitamin D deficiency is so frequent in older patients (aged 65 years and older) that the international consensus does not recommend routine vitamin D measurement. Assessment of overall health status is a cornerstone before considering vitamin D supplementation, as the effect of vitamin D supplementation has only been demonstrated in vulnerable or dependent but not for robust older patients. The effect of the different modalities of oral vitamin D supplementation are equivalent : 800-1'200 IU/day, 10'000 IU/week or 30'000-50'000 IU/month. Monitoring of vitamin D blood level monitoring is not necessary because of a large therapeutic margin. In the presence of osteoporosis, a dietary or supplementation intake of 1'200 mg per day of calcium should be added.