Incidence rates for hip fracture in the United States were estimated using non-federal hospital discharges from the National Hospital Discharge Survey for the years 1974-1979. Age-specific incidence curves for women and for men showed similar patterns of increase in risk with age, with risks approximately doubling every five years after age 50. Age-specific rates by five-year age groups were compared among the four race-sex groups. No significant differences were observed between Black females, Black males, and White males. In contrast, rates for White females were one and one-half to four times those for Black females after age 40 and were approximately double those for White males after age 50. Analysis based on an independent data source of non-federal hospital discharges in Washington, DC confirmed these relationships. In the Washington study, White women were at twice the risk for hip fracture (controlled for age) compared with Black women and at 2.7 times the risk for hip fracture (controlled for age) compared to White men. No significant differences were observed between Black women and Black men.