Background: Implant supported over denture is a very common treatment modality in edentulous patients. Especially 2 implant supported mandibular (OD-1) type of prosthesis is very widely used by clinicians. These over dentures can be used with varying attachment systems. This systematic review compares two implant attachment systems i.e. Ball and Locator to know which one provided better retention. Results: A total number of 94 articles were identified through the electronic search. Only 3 articles were included on the basis of inclusion and exclusion criteria. All the 3 articles were reviewed by the two authors for their study characteristic. All the articles showed varying results regarding retention characteristics provided by both attachment systems. Conclusion: We can conclude that Locator attachment systems are relatively better than ball attachment systems.