The aims of this study are to determine the effect of different polymerization treatment on the transverse strength and residual monomer of auto polymerized acrylic denture base. Materials and Methods: Sixteen samples of heat cured acrylic resin were prepared as a control samples. Eighty samples of auto polymerized acrylic resin were prepared with different polymerization treatments to be tested for transverse strength and residual monomer concentration. These polymerization treatments were carried out by: (1) Open air polymerization treatment, (2) Under hydraulic pressure, (3) Under clamp pressure, (4) Water bath post polymerization. (5) Microwave post polymerization. One half of specimens were subjected to transverse strength test and another one subjected to residual monomer test. Data were analyzed using analysis of variance and Duncan's Multiple Range Test. Results: The result of this study showed that the microwave post polymerization treatment had significantly higher transverse strength, and also showed that the residual monomer significantly lower with microwave and water bath post polymerization treatment. Conclusions: The fracture resistance was improved after post polymerization treatment for auto polymerized acrylic denture base with microwave, and the adverse effect of monomer was decreased by water bath and microwave post polymerization treatment.