The effect of antimony addition (0.2, 0.5 and 1wt%) on the microstructure and mechanical properties of Mg–8Zn–4Al–0.2Mn alloy has been studied. Sb-addition to ZA84 alloy refines the ternary Mg 32 (Al,Zn) 49 phase besides forming Mg 3 Sb 2 precipitates and having a little effect on the grain refinement. Both the room and elevated temperature strength properties (yield and ultimate tensile strengths) are found to increase in Sb added alloys with slight reduction in ductility. However, the maximum strength properties are obtained with 0.2wt% Sb-addition. Fractograph of the tensile tested ZA84 alloy shows intergranular and brittle type failure, whereas 0.2% Sb-addition facilitates transgranular fracture, relating to high strength.