Purpose: Implants have been incorporated into removable partial dentures to provide support and retention. The placement of two distal implants has been recommended to transform Kennedy class I to a Kennedy class III situation. The term implant-assisted was employed to describe the use of attachments to improve retention. The aim of this study is to assess the stress and strain behaviour of two different matrix design of ball attachment incorporated into an existing removable partial denture using a 3dimensional finite element analysis (FEA). Material and methods: Two models of partially edentulous mandible (Kennedy class I) were constructed using FEA software. The implant model simulated a commercially available model with a diameter of 4.8 mm and a length of 12 mm. The models were loaded with a vertical force of 120 N. FEA software was used to analyze the stress and strain patterns. Results: Maximum stress/strain values were located around the implants in both models. The ball attachment with titanium matrix system showed higher stress/strain values compared with the elliptical matrix ball attachment. Conclusion: Within the limits of this study, the use of elliptical matrix ball attachment system showed a more favourable stress/strain distribution over the use of the titanium matrix ball attachment system with implant assisted removable partial denture (IARPD). Keywords: attachment, implant, removable partial denture