This study evaluated the influence of methacrylic acid (MA) incorporation on hardness, roughness, and flexural strength of a denture base acrylic resin. Thirty-two circular and 40 rectangular specimens were divided into four groups, according to the concentration of MA substituted into the monomer component of a heat-polymerized acrylic resin, as follows: 0% (Control), 10%, 20% and 50% (v/v). The following properties were assessed: Vickers hardness, surface roughness, and flexural strength. Variables were analyzed by ANOVA/Tukey's test (α=.05). For the four incorporated MA concentrations (0%, 10%, 20% and 50%), the following results were obtained for hardness (19.0±1.4A, 19.6±1.3A, 19.6±0.9A, 14.2±0.6B VHN), surface roughness (0.26±0.05A, 0.17±0.01AB, 0.18±0.03AB, 0.13±0.03B μm) and flexural strengh (96.3±8.3A, 98.8±6.2A, 102.4±8.6A, 106.3±13.7A MPa). The incorporation of MA may cause slight changes in the structure of the tested material, as evidenced by the hardness test. However, the values for surface roughness reduced as MA concentration increased, suggesting that MA addition may improve the acrylic resin texture.