Achilles tendon ruptures that are not immediately recognized and treated are sometimes diagnosed as delayed injuries and may require different surgical repair options based on gap size. The potential complications associated with using an allograft for reconstruction may lead some surgeons to prefer the use of autologous techniques. However, allografts are often considered a salvagement option when large defects are present. In this study, we examined the long-term clinical outcomes and complications of 17 patients who underwent surgical repair for chronic ruptures with large gaps using both autologous and allograft techniques. During an 11-year period, nine patients were treated with autologous techniques (mean gap of 4.33 ± 1.32 cm) and Achilles allograft reconstruction was performed in eight patients (47.1%) (mean gap of 7.75 ± 0.89 cm). At a mean of 82 ± 36.61 months of follow-up, all 17 patients (100%) were able to perform a single heel rise and improved AOFAS (American Orthopaedic Foot and Ankle Society) and ATRS (Achilles Tendon Total Rupture Score) scores. No infections, complications, or re-ruptures were recorded at the end of the follow-up. No significant differences were found in the AOFAS and ATRS scales between both techniques. When an extensive defect is present, the reconstruction with an Achilles tendon allograft can be considered a proper treatment option, as it does not show a higher rate of complications than autologous techniques achieving similar functional outcomes.