Because of the increasing number of elderly people in the United States, the total number of hip fractures in persons 50 years and older will rise from 238,000 to 512,000 by the year 2040, with a concomitant increase in avoidable deaths, disability, and medical costs. The total annual cost of hip fractures (in 1984 dollars) will increase from approximately 7.2 billion dollars currently to 16 billion dollars in the year 2040. Universal use of estrogen therapy by postmenopausal white women may slow but not prevent this rise in hip fractures. New, effective, and widely applicable strategies to prevent hip fractures are urgently needed.