Introduction:Heat cure acrylic resins are the most commonly used denture base materials. The important limitation is they may act as reservoir of microorganisms. The adherence of microorganisms can be reduced by chemical modification of the surface charge of denture base resin. Incorporation of methacrylic acid (MA) in the denture base resin gives a negative surface charge. A denture base having a negative surface charge may hinder the initial adhesion of microorganisms through repulsive electrostatic forces.Aims and Objectives:The present in vitro study was performed to determine the effect of addition of antimicrobial agent MA on the flexural strength and surface roughness of heat cure denture base resin.Materials and Methods:A total of 90 heat cure acrylic specimens were prepared. Of 90 specimens, 30 were prepared as Group I control group without addition of MA. Groups II and III specimens were prepared by adding 10% and 20% MA, respectively. Using universal testing machine and surface roughness tester, flexural strength and surface roughness of specimens measured.Results:In the present study, decrease in the flexural strength was observed when the concentration of the MA increased in the denture base resin. A slight increase in the surface roughness was observed as the concentration of MA increased.