Despite the importance of fractures as an economic and health problem, and consequent interest in osteoporosis, few workers have previously attempted to define the overall incidence of fracture. This population based study was based in the Accident and Emergency Department of Cardiff Royal Infirmary and identified all patients presenting with fractures of any type. Over a single year a total of 6467 fractures were identified among the 306,600 people who live in the city of Cardiff. This gives an overall fracture incidence of 21.1/1000/year, (23.5/1000/year in males and 18.8/1000/year in females); a result very similar to those from similar work in the USA, Australia and Norway. This result is over twice the previous estimate of fracture incidence in the UK; the figure of 9/1000/year from the only equivalent study performed since the 1960s. In part, this discrepancy appears to reflect our more rigorous definition of the study population, and our improved ascertainment of minor fractures. We believe our result to offer the most accurate estimate of fracture incidence currently available for a UK population.