A classification system for ankle fractures was developed. The system was based on 2 general fracture divisions, namely uni-, bi-, and tri-malleolar ankle fractures, and the localisation of the fracture at the level of the fibula. The use of the system in 612 ankle fractures that were surgically treated at the Leuven University Hospital between 1978 and 1988 led to the following conclusions: 1. All the 612 ankle fractures could be classified without ambiguity. 2. The system was easy workable also for young residents and physiotherapists. 3. It was accessible to repetition, allowing for comparisons between different subjects. 4. Taking into account the type of fracture, the final result could be predicted.