Background <p>The annual incidence of Achilles tendon ruptures has increased by almost 3%. Despite the large amount of data available on post-injury treatment, there is a lack of evidence-based criteria to guide return to running after surgery.</p> Objective <p>The aim of this study was to reach a consensus among experts on the criteria for resuming running following surgery for Achilles tendon rupture.</p> Methods <p>Thirty-five international Achilles tendon experts were invited to participate in this modified Delphi study. The study was conducted in three rounds, with a threshold of 75% agreement (or disagreement) required for an item to achieve consensus. Sixteen clinical criteria were submitted to the expert panel. A five-point Likert scale was used. The study was conducted between January and June 2025.</p> Results <p>Eight criteria achieved consensus after three rounds: seven criteria reached consensus for inclusion, and one criterion reached consensus for exclusion (calf circumference symmetry). The seven criteria were (1) the absence of pain in daily life; (2) the absence of pain during and after rehabilitation sessions; (3) walking without limping; (4) the ability to walk on tiptoes; (5) the ability to perform ten single-leg heel rises; (6) good single-leg balance; and (7) the patient feeling psychologically ready to resume running.</p> Conclusion <p>An expert consensus on the criteria to return to running after surgery for Achilles tendon rupture has been developed. These criteria, agreed by experts, may inform clinical decision making regarding return to running, but they require prospective validation before they can be used as decision rules. Further studies are needed to refine these criteria and evaluate their impact on functional outcomes during the return-to-running phase.</p>