The cases of twenty-six patients who had a reconstructive surgical procedure for treatment of a malunion of a displaced fracture of the fibula were evaluated. In these patients, who had pain, swelling of the ankle, and stiffness at an average of six years after the injury, the malunions were classified radiographically as either occult (eighteen patients) or overt (eight patients). An occult malunion was one in which the talus remained in its normal position, but the lateral malleolus showed residual displacement, characterized by external rotation and shortening. In an overt malunion, there were similar changes in the lateral malleolus, but the talus was displaced. All of the patients were treated by osteotomy of the lateral malleolus to correct the external rotation and shortening, to reduce the lateral subluxation of the anterior aspect of the tibiofibular joint, and to restore the stability of the talus. At an average follow-up of seven years (range, six months to eleven years), twenty of the twenty-six patients were able to resume the preinjury level of activity; three had improvement in the ability to walk and in the level of functional activity, although they still had intermittent pain; and three had not benefited from the procedure.