Background: To evaluate the cost-effectiveness of a reduction in the number of routine radiographs in the follow-up of patients with ankle fractures. Methods: We performed an economic evaluation alongside the multicentre, randomised WARRIOR trial. Participants were randomised to a reduced imaging follow-up protocol (i.e. radiographs at week 6 and 12 follow-up obtained on clinical indication) or usual care (i.e. routine radiography at weeks 6 and 12). The Olerud & Molander Ankle Score (OMAS) was used to assess ankle function and the EQ-5D-3L was used to estimate Quality-Adjusted Life Years (QALYs). Costs and resource use were assessed using self-reported questionnaires and medical records, and analysed from a societal perspective. Multiple imputation was used for missing data, and data were analysed using seemingly unrelated regression analysis and bootstrapping. Results: In total, 246 patients had data available for analysis (reduced imaging = 118; usual care = 128). Fewer radiographs were obtained in the reduced imaging group (median = 4) compared with the usual-care group (median = 5). Functional outcome was comparable in both groups. The difference in QALYs was - 0.008 (95% CI:-0.06 to 0.04) and the difference in OMAS was 0.73 (95% CI:-5.29 to 6.76). Imaging costs were lower in the reduced imaging group (-€48; 95% CI:- €72 to -€25). All other cost categories did not statistically differ between the groups. The probability of the reduced imaging protocol being cost-effectiveness was 0.45 at a wiliness-to-pay of €20,000 per QALY. Conclusions: Reducing the number of routine follow-up radiographs has a low probability of being cost-effective compared with usual care. Functional outcome, health-related quality of life and societal costs were comparable in both groups, whereas imaging costs were marginally lower in the reduced imaging group. Given this, adherence to a reduced imaging follow-up protocol for those with routine ankle fractures can be followed without sacrificing quality of care, and may result in reduced costs. Trial registration: The trial was registered on 26-05-2014 in the Netherlands Trial Registry, with reference number NL4477 (www.trialregister.nl/trial/4477).