Several investigators have reported the presence of biomechanical, kinematic, anatomic, fiber orientation patterns and biological differences between the anteromedial bundle and the posterolateral bundle of ACL. The purpose of this prospective randomized study was to compare the clinical, instrumental and X-ray outcome of two ACL reconstruction techniques with hamstring tendons: one with a single intra-articular bundle associated to an extra-articular sling, the second with a more anatomic double-bundle technique that reproduces better the native ACL function. From an initial group of 100 patients who underwent ACL reconstruction, 72 patients (35 single bundle plus lateral plasty and 37 double bundle) were evaluated with IKDC, Tegner score, KT2000 arthrometer, Activity Rating Scale, Psychovitality Questionnaire and Ahlback radiographic score at a mean 3 years follow-up. Double-bundle group showed significantly better results regarding IKDC, ROM, Activity Rating Scale and time to return to sport. Also KT 2000 showed significant differences in objective stability. The double-bundle technique for ACL reconstruction described in this paper has demonstrated significantly better subjective, objective and functional results compared with a double-stranded hamstrings plus extra-articular sling at a minimum 3-year follow-up.