This study investigated the effect of the addition of nanohybrid particles (nano lithium silicate, nanoparticles highdensity polyethylene and nanoparticles zirconium oxide) with fiber reinforcement (ultra- high-density polyethylene fiber) on transverse, impact strength and surface hardness of heat cured PMMA. A total of 60 specimens were prepared, 40 specimens of each group were fabricated with dimensions of (65 × 10 × 2.5) mm to conduct the transverse strength and hardness tests, while the remaining 20 specimens of each group were fabricated with dimensions of (80 × 10 × 4) mm to perform the impact strength test. ZrO2 nano-fillers were surface-treated with a saline coupling agent to provide bonding between ZrO2 nanoparticles and PMMA matrix. DC-glow discharge system was utilized for plasma surface treatment to ultra-high density polyethylene fibers (UHDPE) to change fiber surface. The results showed that transverse strength and surface hardness begin to decrease after an increase in the fillers percentage and an extreme rise in the impact strength by the increasing fillers percentage in composites.