This population-based study revealed that 2,519 limb fractures occurring during a 3-year period produced an age-adjusted incidence rate for all limb fractures of 1,596 per 100,000 person-years. Fractures of the upper limb had a bimodal age distribution and were commoner than those of the lower limb, which had a J-shaped age distribution. The most frequent anatomic site was the lower end of the radius and ulna. Limb fractures occurred as solitary events in 93% of cases; only 4% were classified as open and more than half of the total were closed and undisplaced. Fractures were distributed evenly throughout all time periods of the day. The commonest place of fracture occurrence was the home, and the most important direct cause was falls, particularly in females. A wide range of sports activities were a major source of fractures, particularly in younger males. Underlying bone pathology was uncommon, other contributory causes being more important, particularly in the elderly. The increased ratio of metaphyseal to diaphyseal fractures with age indicated a relative loss of cancellous bone in the elderly, but no evidence was found to suggest that elderly women had reduced resistance of bone to impact forces in comparison with elderly men.