Five cats were treated for a fracture of the medial malleolus, 10 for a fracture of the lateral malleolus and 15 for fractures of both malleoli. Open reduction and internal fixation with Kirschner wires (K-wires) with or without a tension band wire was applied to 26 of the fractures. Unilateral-uniplanar or bilateral-uniplanar transarticular external skeletal fixators were applied to provide coaptation in 19 cases and appeared to be well tolerated. In 24 cases fracture healing was assessed radiographically between four and eight weeks after treatment. In seven cases fracture healing was good, in 12 cases it was reasonable, in four cases it was poor and in one case with two fractures healing was poor in one and reasonable in the other. The 12 fractures treated by open reduction and internal fixation with K-wires and a tension band wire all showed evidence of good or reasonable healing. The nine fractures treated by open reduction and internal fixation with K-wires without a tension band wire showed evidence of good or reasonable healing in six cases and poor healing in three cases. Complications occurred in nine of the cats and included persistent talocrural instability, soft tissue necrosis, implant migration and external fixator pin breakage. Twenty-one of the cats were followed up by telephone questionnaire for between 5·5 and 84 months; the owner satisfaction was excellent in 17 cases, good in two cases, moderate in one case and poor in one case.