Mechanical properties of fine-grained Mg alloys processed by powder metallurgy (P/M) and ingot metallurgy (I/M) routes have been investigated by tensile tests at room temperature and 573 K. The superplastic strain rate range for the P/M Mg alloys was higher than that for the I/M Mg alloys. Furthermore, the P/M Mg alloys exhibited higher room temperature strength than the I/M Mg alloys. These excellent mechanical properties of the P/M Mg alloys are attributed to a very small grain size of 0.5 similar to1 mum.