Purpose Current options for treating an Achilles tendon rupture (ATR) include conservative and surgical approaches. Endoscopic lexor hallucis longus (FHL) transfer has been recently proposed to treat acute ruptures, but its cost-efectiveness potential remains to be evaluated. Therefore, the objective of this study was to perform an early cost-efectiveness analysis of endoscopic FHL transfer for acute ATRs, comparing the costs and beneits of current treatments from a societal perspective. Methods A conceptual model was created, with a decision tree, to outline the main health events during the treatment of an acute ATR. The model was parameterized using secondary data. A systematic review of the literature was conducted to gather information on the outcomes of current treatments. Data related to outcomes of endoscopic FHL transfers in acute Achilles ruptures was obtained from a single prospective study. Analysis was limited to the two irst years. The incremental cost-efectiveness ratio was the main outcome used to determine the preferred strategy. A willingness-to-pay threshold of $100,000 per quality-adjusted life-year was used. Sensitivity analyses were performed to determine whether changes in input parameters would cause signiicant deviation from the reference case results. Speciically, a probability sensitivity analysis was conducted using Monte Carlo simulations, and a one-way sensitivity analysis was conducted by sequentially varying each model parameter within a given range. Results For the reference case, incremental cost-efectiveness ratios exceeded the willingness-to-pay threshold for all the surgical approaches. Overall, primary treatment was the main cost driver. Conservative treatment showed the highest direct costs related to the treatment of complications. In the probabilistic sensitivity analysis, at a willingness-to-pay threshold of $100,000, open surgery was cost-efective in 50.9%, minimally invasive surgery in 55.8%, and endoscopic FHL transfer in 72% of the iterations. The model was most sensitive to parameters related to treatment utilities, followed by the costs of primary treatments. Conclusion Surgical treatments have a moderate likelihood of being cost-efective at a willingness-to-pay threshold of $100,000, with endoscopic FHL transfer showing the highest likelihood. Following injury, interventions to improve healthrelated quality of life may be better suited for improved cost-efectiveness. Level of evidence Level III.