Implant–supported overdenture housings are retained in denture base with various types of materials. Inadequate adhesion between the housing and the denture creates a gap that weakens the construct .Surface roughness contributes to plaque accumulation. This study was conducted to evaluate the retention and surface roughness of materials used to retain the housings. 80 polymethyl methacrylate denture base specimens were fabricated and divided into 4 groups depending on the retaining material used to retain the housings in denture base specimen: autopolymerizing acrylic resin (GROUP A),composite resin (GROUP B), pattern resin (GROUP C) and heat polymerizing acrylic resin (GROUP D). SEM images were made to inspect the PMMA denture base–retaining material–housing interfaces for any adhesive failure. The surface roughness of the retaining materials was measured with a profilometer. Statistically significant differences were observed in terms of both retention and surface roughness. Within the limitations of this study it was concluded that Pattern resin was most suitable in terms of both retention and surface roughness.