Tensile ductility of magnesium alloy ZK60 pre-strained by warm equal channel angular extrusion (ECAE) was investigated at 300°C. It was shown that a significant ductility (262%) is achievable with this technique for a fairly high strain rate of 3·10⁻³ s⁻¹. The effect of pre-straining by warm ECAE on twinning under room temperature deformation was also investigated. It was shown that a bi-modal grain structure, whose characteristics are determined by the ECAE route, number of passes and temperature, has a strong effect on the propensity for twinning and mechanical properties, including ductility.