Background: Poly methyl methacrylate (PMMA) is the dominant acrylic that is widely used to produce partial and complete dentures., and its application is often accompanied by the formation of biofilm. The mechanical properties of dentures have been developed by reinforcing with various agents like rubbers, fillers, and fibers. Progressively, novel dental materials reinforcement tactics have been developed following the advancement in Nano dentistry. The aim of this work was the preparation of PMMA/gold nanoparticles (AuNps) to improve the mechanical properties of heat -polymeried PMMA. In the present study, adaptation and color stability were investigated. Adaptation was measured using Euromex microscope and Color stability was evaluated using spectrophotometer. Results: Adaptation of a PMMA/gold nanoparticles (AuNps) were decreased for all groups containing AuNps whatever Color stability of a PMMA/gold nanoparticles (AuNps) were increased for all groups containing AuNps Statistical analysis was performed by means of the SPSS 16 software package. Conclusions: Incorporation of AuNps into heat- polymerized PMMA resin led to increase color stability and decrease adaptation of complete denture base material.