Elderly women and men lose bone at a rate of < or = 1% per year. This results in an increasing risk of most fractures, of which hip fractures account for the greatest proportion of death, disability, and medical costs. Falls are the immediate precipitating factor for about 90% of hip fractures and 80% of other types of fractures in women. Since the rate of bone remodeling increases with age, antiresorptive therapies are likely to be at least as effective in the elderly as in younger adults. Calcium supplementation, for example, slows bone loss more effectively in older women than in those within 5 years of menopause, although the effectiveness of calcium for prevention of fractures remains uncertain. Vitamin D deficiency is more common in the elderly, and supplementation of deficient women appears to slow bone loss, at least during winter. Calcium plus vitamin D may substantially reduce the risk of hip fracture in the frail elderly. A randomized trial showed that estrogen remains effective in preventing vertebral fractures in older women. There is no reason to believe that the effectiveness of other agents would diminish with age. Preventive therapy offers greatest and most immediate benefit to those who have the highest risk of fracture: the elderly, those with previous fractures, those at increased risk of falling, and those with lowest bone mass. Since the relationship between bone mass and risk of fracture remains strong in elderly women, bone mass measurements may also be as useful in the elderly as in younger adults.