Occlusal vertical dimension of full denture's patient should be determined correctly to achieve an optimal result in function including aesthetic aspect of the denture. Differences of occlusal vertikal dimension may influence the strength of musculus masseter and temporalis contraction. Electromyography could showed isometric contraction of both musculus. The aim of this study was to evaluate the influence of different occlusal vertikal dimension to the contraction of both musculus. Denture base: occlusal rims and Electromyography. Neuropack MEM-7132 K (NIHON-KOHDEN) with evaluation program software Lab View 4.1. were used. A quasi experiment was done on patient chosen at Prosthodontics Clinics Faculty of Dentistry University of Indonesia age range from 50-72 years old who need full denture. Occlusal vertical dimension was determined contraction of musculus masseter and temporalis were measured using EMG. Data were analysed using One Way (ANOVA) with 95% different or p<0.05. The result showed that at the proper occlusal vertical dimension, the strength of the musculus masseter and temporalis was the highest in the comparison to the higher and lower occlusal vertical dimension. It can be concluded that occlusal vertical dimension has significant influence to muscle contraction especially musculus masseter superficial and musculus temporalis anterior.