One hundred and three displaced malleolar fractures of the ankle joint were treated by one orthopaedic firm between 1968 and 1974. Originally, 150 patients were reviewed, but 47 patients were excluded from the series for the following reasons: associated fractures of the lower tibia (10), associated fractures of the talus (3), inadequate follow-up (15) and patients lost to follow-up (19). Only patients who were followed up for at least one year were included in the series. The purpose of this study is to present the results obtained by treating displaced malleolar fractures using AO instrumentation.