Based on the investigation of equilibrium and non-equilibrium phase transformations in both heat-treated and as-cast Zn-Al based alloys, 0.3% Nd, La and Ce were added to a Zn-Al based alloy, ZA-27, the microstructure and ageing behavior of this alloy being studied. A similar sequence of phase transformations as is known to occur in the parent as-cast Zn-Al based ZA-27 was observed. It was found also that the rare-earth Zn-rich phase E was typically angular in shape and decomposed after a long period of ageing.