ABSTRACT This study compares the wear changes and retention between two stud attachments “Ball” and “Novaloc” used for implanted supported mandibular overdenture. Two epoxy resin models represented completely edentulous patients were duplicated from an educational cast and prepared to receive two implant analogues in the canine area. Two different attachment systems were used: the first one was Ball attachment with a metal housing of gold insert, the second one was Novaloc with a PEEK matrix & insert. They were divided randomly into two groups. Two overdentures were fabricated for each group. The pick-up proceeded as conventional methods. Robota simulator applied multiple cycles mimicking the insertion and removal of the overdentures at the baseline, 500 cycles, 1000 cycles, 1500 cycles and 2000 cycles. Digital microscope evaluated the wear behavior of each attachment during these different cycles. Attachments retention was measured using universal testing machine. Wear changes comparison of both groups revealed that Novaloc group was significantly higher than Ball group between baseline and 2000 cycles. Regarding retention, comparison between both groups revealed that retention Novaloc group was significantly lower (P<0.05) than Ball group at baseline, 1000 cycles, 1500 cycles & 2000 cycles. The rate of wear was higher in Novaloc attachment which had PEEK Inserts than those of ball attachments with its gold precious alloy inserts. Regarding retention of both attachments, the Ball attachments had a significant higher initial and final retention values than the Novaloc attachments. Keywords: Novaloc attachment, Ball attachment, Retention, Wear changes