The influence of Ce additions to AM50 magnesium alloy prepared by high pressure die casting on the microstructure and corrosion behaviour has been investigated. The corrosion behaviour was evaluated by hydrogen evolution, salt spray, potentiodynamic polarization and electrochemical impedance experiments. The results show that Ce addition promotes the formation of Al ₁₁Ce ₃ phase and reduces the amount of β-phase (Mg ₁₇Al ₁₂). The corrosion resistance is improved with increasing Ce content which can be attributed to the formation of Al ₁₁Ce ₃ phase, reduction of β-phase (reduced galvanic effects) and higher purity of AME50X alloys (melt cleaning effects).