Statement of problem: Adhesive failure between the liner and the denture base creates an environment for potential bacterial growth and accelerated breakdown of the soft liner resulting in a deteriorating prosthesis. Purpose This study evaluated the effect of lased preparation on the interracial bonding of polymethyl methacrylate and auto polymerization silicon-based soft lining material. Materials and Methods: Ten complete mandibular dentures were selected to be relining, half of the denture was laser Er: YAG treated and the other half untreated (control). Then the silicone-based soft liner material (Ufi-Gel P) was applied. The peel bond strength test was examined by Instron Universal Testing Machine at crosshead speed of 30mm/min. T-student test was used to analyze the data (α=0.05). Results: Altering the polymethyl methacrylate surface by laser Er:YAG significantly increased the peel strengths for the silicone lining material with the denture base in compere with the controls(P<0.05). Conclusions: Results of this study imply that mechanical surface preparation (laser irradiation) of denture bases before application of a resilient liner shows higher peel bond strength.