By means of a simple and easy classification, namely uni, bi- and trimalleolar ankle fractures, and the localization of the fracture at the level of the fibula; all of the 612 ankle fractures that were surgically treated at the Leuven University Hospital were easily classified. In 590 cases the results were collected 1 year after the operation by means of an evaluation system based on symptoms, clinical findings and radiographic findings. The influence of the type of fracture was analysed and led to the following conclusion: 1. Unimalleolar fractures have a better prognosis than trimalleolar fractures. 2. An isolated medial malleolar fracture gives a worse final result than an isolated lateral malleolar fracture. 3. Multimalleolar fractures, including the medial malleolus, have a worse prognosis than multimalleolar fractures without medial malleolar fractures. 4. Even after perfect internal fixation, the presence of a posterior fragment larger than one-third of the articular surface leads to a worse final result than a small unfixed fragment. 5. Weber's classification may not be useful for prognosis.