The effect of rolling reduction of the last pass on the dislocation slip and twinning behavior during direct hot rolling of a cast WE43 magnesium alloy at 480 °C was investigated. The results showed that prismatic áa？ slip was always the main deformation mode during rolling at 480 °C. In addition, the activated twinning type was associated with rolling reduction. The extension twinning was activated at a slight rolling reduction (2%), while compression twinning and - double twinning were activated at larger rolling reduction (12% and 20%). Schmid factor calculation showed that the activation of extension twin variants followed the Schmid Law, whereas the activation of compression twin variants did not follow it. Even if the rolling reduction reached 20%, almost no dynamic recrystallization (DRX) grains were found, presumably because the amount of deformation required for DRX to occur was not reached.