The main goal of this research is to investigate the effect of copper on compressive strength of dental amalgam. For this purpose amalgam capsules with two different content of copper were used. Cylindrical samples with diameter to height ratio 1 to 2, were prepared via molding method. To evaluate the role of copper element on compressive strength, com-pression test was done at different strain rates i.e. 0.02, 0.2, 0.4 and 2 min –1 . The results and microscopic evaluations showed that an increase in copper content in amalgam caused to eliminate gamma2 phase and leaded to promote com-pressive strength.