The extent to which a fracture at one skeletal site predicts further fractures at other sites remains uncertain. We addressed this issue using information from the UK General Practice Research Database, which contains the medical records of general practitioners; our study population consisted of all patients aged 20 years or older with an incident fracture during 1988 to 1998. We identified 222 369 subjects (119 317 women, 103 052 men) who had sustained at least one fracture during follow-up. There was a 2- to 3-fold increase in the risk of subsequent fractures at different skeletal sites. A patient with a radius/ulna fracture had a standardized incidence ratio (SIR) of 3.0 (95% confidence interval 2.9-3.1) for fractures at a different skeletal site; for initial vertebral fracture, this ratio was 2.9 (2.8-3.1) and for initial femur/hip fracture it was 2.6 (2.5-2.7). The SIRs were generally higher among men than women. Men aged 65-74 years with a radius/ulna fracture or vertebral fracture had substantially higher rates of subsequent femur/hip fractures than expected; SIRs were 6.0 (3.4-9.9) and 13.4 (7.3-22.5). Corresponding SIRs among women of similar age were 3.3 (2.8-3.9) and 5.8 (4.1-8.1), respectively. Men and women aged 65 years or older with a vertebral fracture had a 5-year risk of femur/hip fracture of 6.7% and 13.3%, respectively. Our results indicate that fractures at any site are strong risk factors for subsequent fractures, among both elderly men and women.