The initial ankle radiographs of 144 patients with ankle injuries were used to predict the total extent of ankle injury. Using the operative, clinical and radiographic findings, each injury was then classified according to the Lauge-Hansen system. Three patterns of lateral mallecolar fracture were unique to specific mechanisms of injury, with transverse fractures occurring in supination-adduction injuries, spiral fractures in supination lateral rotation injuries, and bending fractures in pronation abduction injuries. Vertical medial mallecolar fractures occurred only with supination-adduction injuries. Oblique and transverse medial malleolar fractures were not characteristic of a particular mechanism of injury. The complete extent of injury was accurately determined by the ankle radiographs in all but four patients. In these, the deltoid ligament tears could not be predicted by the radiographic findings.