Forty-seven patients over the age of 55 years with a displaced fracture of the ankle were entered into a prospective, randomised study in order to compare open reduction and internal fixation with closed treatment in a plaster cast; 36 were reviewed after a mean of 27 months. The outcome was assessed clinically, radiologically and functionally using the Olerud score. The results showed that anatomical reduction was significantly less reliable (p = 0.03) and loss of reduction significantly more common (p = 0.001) in the group with closed treatment. Those managed by open reduction and internal fixation had a significantly higher functional outcome score (p = 0.03) and a significantly better range of movement of the ankle (p = 0.044) at review.