This parallel study aimed to evaluate the retention values of Poly Ether Ether Ketone (PEEK) telescopic attachment with different matrix materials (PEEK, Titanium) for implant retained mandibular overdenture. Materials and Methods: Fourteen completely edentulous patients were selected for this study, to receive mandibular complete overdentures supported by 2 implants in the canine region using a surgical guide. (CAD/CAM) PEEK telescopic attachment was fabricated to retain overdenture; the patients were divided into two groups 7 each according to matrix material Group A: matrix part of the attachment was constructed by PEEK Group B: patient's matrix part of the attachment was constructed by Titanium Finally; direct pick-up of the matrix was done. Retention values were measured at the time of overdenture insertion (T0), after 6 months of use (T6), and After 12 months used (T12). Results: There was a highly significant decrease with time for each group and a highly significant difference for comparing two groups in each interval. Conclusion: Within the limitation of this study, it was concluded that: PEEK telescopic attachment with titanium matrix attains better values of retention with time when compared to PEEK matrix