Osteoporosis affects millions of postmenopausal women in the United States alone. For white women who reach 50 years of age, the lifetime risk of vertebral fracture is about one in three, and that for hip fracture is one in six. One tenth to one fifth of the women who have a hip fracture die within a year after it occurs, and one quarter must move permanently to a nursing home. Although potentially devastating, osteoporotic fractures can be prevented. Adequate calcium intake (at least 1200 mg daily for postmenopausal women) and vitamin D intake (400 to 800 IU daily) and regular . . .