We have analysed 249 consecutive fractures of the humeral shaft treated over a three-year period. The fractures were defined by their AO morphology, position, the age and gender of the patient and the mechanism of injury. Open fractures were classified using the Gustilo system and soft-tissue injury, and closed fractures using the Tscherne system. The fractures were classified as AO type A in 63.3%, type B in 26.2% and type C in 10.4%. Most (60%) occurred in the middle third of the diaphysis with 30% in the proximal and 10% in the distal third. The severity of the fracture and soft-tissue injury was greater with increasing injury severity. Less than 10% of the fractures were open. There was a bimodal age distribution with a peak in the third decade as a result of moderate to severe injury in men and a larger peak in the seventh decade after a simple fall in women.