Anterior cruciate ligament (ACL) reconstruction using hamstring tendon autograft is a common procedure in orthopedic surgery to treat ACL rupture. Graft diameter is very important in successfulness of ACL reconstruction. The purpose of this study was to evaluate the influence of hamstring autograft diameter on patient-reported functional scores following ACL reconstruction. The diameter of grafts were collected retrospectively from medical records of the patients who underwent primary ACL reconstruction with hamstring autograft in the Soeradji Tirtonegoro General Hospital, Klaten, Central Java.