Polymeric dental restorative composites (PDRC) containing urethane dimethacrylate was prepared using the visible light activation system. The resin matrix system of PDRC was 2,2'-bis-[4-(3-methacryloxy-2-hydroxypropoxy)phenyl] propane diluted with triethyleneglycoldimethacrylate and/or urethane dimethacrylate (UDMA). The hybrid-filler system was used as an filler component. To improve the dispersibility of the filler in the PDRC, its surface was hydrophobically coupled with silane compound. In the present study, effect of UDMA diluent on the mechanical properties of the PDRC was investigated by measuring the diametral tensile strength, flexural strength, and flexural modulus values. Scanning electron microscopy study indicated the superior surface characteristics of PDRC product prepared herein.