One hundred and thirty-eight patients with a closed grade-4 supination-external rotation or pronation-external rotation ankle fracture (Lauge-Hansen classification) who were seen in the emergency room of the University of Chicago Hospitals were entered into a randomized study of the results of various methods of treatment. Ninety-six patients with satisfactory initial closed reduction were randomized between continued closed treatment in a plaster cast and open reduction with rigid internal fixation according to the techniques of the Association for the Study of Internal Fixation (ASIF). Forty-two patients with unsatisfactory closed reduction were randomized between open reduction with internal fixation of only the medial malleolus and open reduction with rigid internal fixation according to the ASIF techniques. Of the 138 patients who were admitted to the study, only seventy-one (51 per cent) could be followed for an average of 3.5 years (a typical return rate of urban trauma centers). The outcomes were evaluated by a scoring system that included clinical, anatomical, and arthritis scores. Statistical analysis of the data showed that, of the patients with initial satisfactory closed reduction, the ones treated by open reduction and rigid internal fixation had significantly higher total scores, particularly the patients who were more than fifty years old and those with a medial malleolar fracture. The small number of patients with unsatisfactory closed reduction who were treated by one of the two types of open reduction and internal fixation and were available for follow-up precluded drawing any conclusions about the superiority of one method of internal fixation over the other in that group. The difference in the talocrural angle between the injured and normal sides was the only statistically significant radiographic indicator of a good prognosis.