The clinical features of 311 patients with apparently sprained ankles were analysed and compared with radiographs. Measurable swelling was found to be a constant feature of ankle fractures and bruising was very common. The incidence of fractures increased with age. No other physical sign nor the history was useful in predicting fracture in this context. It is concluded that advanced age, bruising and particularly swelling are strong indications for ankle radiography and the absence of swelling is a strong contraindication.