¹ Ali Hamed El-Shoukouki, ² El-Sayed Abdel-Khalek, ³ RbieAkrim Mahmud ¹  Professor of removable prosthodontics, faculty of dentistry ,Mansoura University ² Lecturer of removable prosthodontics, faculty of dentistry, Mansoura University 3 BDS, faculty of dentistry, Tripoli University Abstract: Purpose: This in-lab study was performed to estimate the time influence of resilient liner rather than clip as related to retentive force for mandibular implant overdenture (at time of   insertion, after 15 days ,after 30 days, after 45 days, after 60days and after 90days) time. Materials and Methods: This in-vitro study was carried out on acrylic model representing mandibular complete edentulous and auto-polymerzied soft liner material was covered ridge. Two implants were installed into in canines regions bilateral in acrylic model which were connected by round bar attachment. Then Molloplast-B heat cure soft liner bar clip was prepared. Five overdentures were fabricated. The retention test for overdentures was measured by using a Digital Force-meter Machine according to the time of the storage time of specimen in normal saline. ( zero time, 15 days, after 30 days, after 45days and after 90days time). Then data was collected and statistically analyzed. Results: the high mean retentive force of resilient soft liner bar clip was at 45 days(X=1.82 N), while the low mean retentive force of resilient soft liner bar clip was at 90 days (X=1.28 N) and there was significantly differ at 5% level of significant between multivariable analysis of time factor . Conclusions: Resilient soft liner bar clip acting as bar framework to optimize mandibular implant overdenture retention and it is promise in retention of mandibular implant overdenture.