A potential new grain refiner, ZnO, for magnesium alloys was identified using the edge-to-edge matching crystallographic model. The effects of various levels of ZnO additions on the grain size of pure magnesium and a Mg-Zn alloy were investigated. Experimental results show that an addition of 3 wt.% ZnO powder to pure magnesium reduces the grain size from 1100 to 410 mu m. The grain size of a Mg-Zn alloy can also be decreased from 420 to 310 mu m when 1 wt.% ZnO powder is added. (c) 2007 Elsevier B.V. All rights reserved.