Abstract: Objective：This study intended to investigate the mechanical properties of polymethyl methyacrylate denture base into which zinc oxide whiskers was added. Methods：We conducted the study on five groups divided according to zinc oxide whiskers content which was added to the denture base including control at the rate of 1%, 3%, 5%, and 7%. ISO standard was applied in mechanical tests, and the fractured surfaces of specimens were examined under SEM. Results：Flexural strength, flexural modulus and hardness of composite material increased with the increasing content of zinc oxide whiskers in a limited range. The results showed that the flexural strength, flexural modulus and hardness of composite material rising up to (109.00±2.70) MPa, (3645.30±198.68) MPa, (20.57±0.85) kg/mm2, when the amount of zinc oxide whiskers in the base made up 5% of the total. And the flexural strength of the composites was enhanced by 18.29%, flexural modulus by 16.07%, and hardness by 29.9% compared with that of the control group. Conclusions：Zinc oxide whiskers filler significantly enhanced mechanical properties of denture base.