To estimate the incidence of fracture of the proximal end of the femur in people aged 50 years or older living in the Quebec area in 1971, 1976 and 1981 we determined the number of admissions for such fractures to the 15 acute care hospitals in the region. From 1971 to 1981 the number of fractures increased by 71%; the increases for those aged 75 to 84 years and 85 years or over were 98% and 118% respectively. The variation is only partly explained by changes in sex and age distribution of the population; the incidence rates also increased. Among men aged 75 to 84 years the incidence rate per 1000 person-years rose from 2.63 in 1971 to 5.22 in 1981, an increase of 98%; the corresponding figures for men aged 85 years or more were 9.76 and 16.91, an increase of 73%. Among women aged 75 to 84 years the rate rose from 7.28 to 8.81, an increase of 21%; the corresponding figures for women aged 85 years or more were 20.40 and 24.27, an increase of 21% and 19% respectively.