Aim: The aim of this study was to radiographically evaluate ball versus locator attachment systems for mandibular single implant-retained complete over denture. Subjects and Methods: Twenty completely edentulous patients were randomly selected from the Outpatient Clinic, Department of Removable Prosthodontics, Faculty of Dental Medicine, (Boys, Cairo), Al-Azhar University. The patients divided into groups, group I received single implant retained overdenture with ball and socket while group II received single implant retained overdenture with locator attachment. Radiographic evaluation was carried out with periapical radiograph using the extension cone parallel technique. Results: Group I recorded higher bone loss than group after one year of overdenture insertion and the difference was significant. Conclusion: Locator attachment provides optimal results regarding preservation of bone around implant fixture of implant retained overdenture than those with ball and socket attachment.