The long-term results of 74 cases of simple traumatic dislocation of the hip are reported and the effects of the cause of dislocation and of the occupation and age of the patient on the prognosis are assessed. The average follow-up was 14.65 years. Contrary to the widely held view that there are no long-term complications of this injury, we found that, overall, 24 per cent of the dislocated hips went on to develop osteoarthritis. The incidence was highest in manual workers with 37.5 per cent of miners injured in car accidents developing osteoarthritis compared with only 20 per cent of the sedentary workers. The incidence of osteoarthritis in miners injured in pit accidents was 45 per cent compared with only 17 per cent for those involved in motor cycle accidents. These differences could be due to continued heavy work after the accident rather than to any difference in the violence of the initial injury. The incidence of osteoarthritis was highest in patients aged between 31 and 40 years and, as expected, was found to increase with length of follow-up.