Results of an exploratory study of the effect of strain rate on metal behaviour during reversed loading are presented. All test specimens were made from commercially pure aluminium; these specimens were prestrained in tension and then strained in compression at several strain rates. The effect of tensile prestrain rate and compressive strain rate is shown. Also, the compressive strain rate dependence of aluminium with a tensile prestrain is compared to the strain rate dependence of aluminium with no prestrain. © 1968.