A Rotary-die equal-channel angular pressing (RD-ECAP) process was applied to improve the impact toughness of Al-11mass%Si eutectic alloy (AC8A). RD-ECAP was effective at improving impact toughness: the impact toughness increased as the number of pressings increased. In addition, the effects of heat treatments on impact toughness were investigated. When samples were heat-treated under the T6 condition before the RD-ECAP process, they exhibited a higher impact toughness than the samples without T6 treatments. The absorbed energy of the heattreated samples followed by RD-ECAP 4 times was 4.32 J/cm 2 , which was much higher than that of the non-heat-treated samples, 2.89 J/cm 2 , and three times higher than the value of the heat-treated but non-processed samples, 1.08 J/cm 2 . The results show that the combination of the T6 treatment and the RD-ECAP process is more effective at improving the impact toughness, compared to applying the RD-ECAP process alone.