An incidence study of fractures of the proximal femur has been conducted over a 10-year period. The results show a doubling of the fracture rate in each decade of life after age 50 years. A comparison of age-adjusted fracture rates with populations in different countries shows that in both men and women, the hip fracture is highest in the United States population examined in this study. The fracture rate is much greater in women than in men, and by age 90 years, about 32% of women and 17% of men had suffered a fracture. An estimate of the number of proximal hip fractures occurring in the United States suggests that approximately 113,000 women and 34,000 men older than 50 years of age will suffer a hip fracture each year. This represents a considerable cost, approaching one billion dollars annually, to health care in the United States.