xiii ABSTRACT Acrylic resin or poly methyl methacrylate (PMMA) is one of biomaterial that has been used extensively in dentistry include temporary crown, physiological tray, and denture base plate. Self-cure acrylic resin doesn’t need thermal energy when polymerizing. However, monomer utilizing in acrylic resin has unpleasant aroma that disturb dentist and dental laboratory. Then freshness aroma from mint leaves (Mentha piperita L.) without affecting the transverse strength of acrylic resin is needed. This study was designed to evaluate the effect of adding extract essential oil mint leaves in transverse strength of self-cure acrylic resin. Fifteen sample of each acrylic resin 64mm x10mmx 3,3mm dimensions were divided into three groups with five samples in each. One group as a control and others were submitted to adding extract volume 0,25ml, 0,5ml. Essential oil of mint leaves was obtained from water steam distillation. The transverse strength measured by three point bending test using Universal Testing Machine. The data were analyzed by means of one-way analysis of variance (ANOVA) and Post-Hoc LSD. The transverse strength of self-cure acrylic resin values showed statistically significant differences among experimental group which adding extract volume 0,25ml and 0,5ml (p<0.05), however adding extract 0,25ml did not greatly affect in comparison to the control group (p=0.488). Adding of low volume (0,25ml) essential oil mint leaves (Mentha piperita L.) did not affect significantly to the transverse strength of self-cure acrylic resin.