This study was conducted to observe the effect of different monomers on tensile and flexural strengths of poly (methyl methacrylate) (PMMA) denture base resin when they were used as a liquid component. A conventional heat-cured denture base polymer powder was mixed with ethyl, isobutyl and tert-butyl methacrylate monomers, respectively. After the polymerization process was completed, the tensile and flexural strength values of these specimens were compared with those that of PMMA resin specimens polymerized with methyl methacrylate monomer (MMA). Tensile specimens were prepared in a dumbbell shape using a stainless steel mold constructed according to ASTM D638M-91a. Rectangular flexural specimens were prepared as designated in ASTM D790M-92. Each group was subjected to tensile strength and flexural strength tests using a crosshead speed of 50 mm min(-1) using a universal testing machine. In addition to mechanical tests, the structural change in the acrylic resin specimens prepared with different monomers was observed by Fourier Transform Infrared Spectrometer with Attenuated Total Reflectance unit (FTIR-ATR). The differences in the tensile strength values of all specimens were not found to be statistically significant (p > 0.05), whereas, the flexural strength values showed statistical differences among the groups tested (p < 0.05). In the results of the tests performed, it was reached that the flexural and tensile strength values of acrylic resins obtained by various methacrylate monomers were different. It can be said that these acrylic resins can be used for various aims in the different fields as well as in dentistry field.