Aims. The aim of this study was to compare the functional and radiological outcomes and the complication rate after nail and plate fixation of unstable fractures of the ankle in elderly patients. Methods. In this multicentre study, 120 patients aged ≥ 60 years with an acute unstable AO/OTA type 44-B fracture of the ankle were randomized to fixation with either a nail or a plate and followed for 24 months after surgery. The primary outcome measure was the American Orthopaedic Foot and Ankle Society (AOFAS) Ankle-Hindfoot score. Secondary outcome measures were the Manchester-Oxford Foot Questionnaire, the Olerud and Molander Ankle score, the EuroQol five-dimension questionnaire, a visual analogue score for pain, complications, the quality of reduction of the fracture, nonunion, and the development of osteoarthritis. Results. At 24 months, the median AOFAS score was equivalent in the two groups (nail 90 (interquartile range (IQR) 82 to 100), plate 95 (IQR 87 to 100), p = 0.478). There were statistically more complications and secondary operations after nail than plate fixation (p = 0.024 and p = 0.028, respectively). There were no other significant differences in the outcomes between the two groups. Conclusion. The functional outcome after nail and plate fixation was equivalent; however, the complication rate and number of secondary operations was significantly higher after nail fixation. These results suggest that plate fixation should usually be the treatment of choice for unstable ankle fractures in the elderly. Cite this article: Bone Joint J 2023;105-B(1):72–81