The objective of this study was to evaluate the flexural strength of denture base resin reinforced with glass fibers and with a laboratorial composite resin. Group G1 was formed with specimens made of acrylic resin. Group G2 was formed with the same acrylic resin but reinforced with a glass-fiber system, and G3 was reinforced with the composite resin. A flexural strength test was performed in all groups (n=10). The mean value for the G1 was 86.70 MPa +/- 6.48, for G2 it was 86.60 MPa +/- 15.01 and for G3 it was 108.90 + 11.03. The addition of glass fiber did not increase the flexural strength however the use of a resin-based composite produced significant reinforcement.