This study was intended at evaluating the impact of adding gold nanoparticles (AuNPs) on the characteristics of heat-cured acrylic denture base resin. Heat cured polymethyl methacrylate (PMMA) samplings, each one had a dimension of 50 mm length, 30 mm width and thickness of 0.5±0.1 mm, enclose various sizes (10 and 20 nm) of gold nanoparticles were formulated, where free nanoparticle samples were deemed as the control group (N=6 specimens for each group). Flex¬ural strength, color changes, surface roughness, and hardness of all specimens were then assessed. Data were amassed, statistically evaluated, and tabulated. It was fulfilled that statistically signifi¬cant decreases in the flexural strength were observed with the increase in gold nanoparticle size, where group 3 (with 20% nanogold particle size) was peaked. However, no significant differences in PMMA color changes, superficial roughness, and hardness were observed in the groups cover¬ing various sizes of AuNPs. It was concluded that The flexural strength of heat-cured PMMA-resin showed significantly decreases with the addition of AuNPs, particularly with the particle’s sizes of 20nm.