The objective of this study was to estimate the incidence of hip fracture in the canton of Vaud, Switzerland (total population 584,000), for the period 1986-1991 using routine hospital discharge data collected by the Cantonal Service of Statistical Research and Information (SCRIS). For the survey period, the estimated average annual crude incidence rate of hip fractures was 167 per 100,000 persons aged 20 or older (241 for women and 84 for men). For the population aged 50 years or older, the crude incidence rate was 388 per 100,000 persons (546 for women and 185 for men). The average annual age-specific rates rose exponentially by successive 5-year age groups. The median age of patients at the time of the fracture was 82 years in women and 74 years in men. There was no significant difference between the total number of cervical and trochanteric fractures. Between the ages of 20 and 84 years, the cumulative risk for a woman to be admitted to hospital with a hip fracture was twice that of a man (15.8% vs 7.8%). From 1986 to 1991, the age- and sex-adjusted incidence, like the ratio of cervical to trochanteric fractures, did not show any significant trend, although it was consistent with an increase in men (p = 0.09). However, the annual number of fractures rose from 644 to 776, particularly among very aged men. The mean length of stay in the acute care hospital fell from 38 days in 1986 to 25 days in 1991.(ABSTRACT TRUNCATED AT 250 WORDS)