The effect of iron on the grain refinement of high-purity Mg–3%Al and Mg–9%Al alloys has been investigated using anhydrous FeCl3 as an iron additive at 750 °C in carbon-free aluminium titanite crucibles. It was shown that grain refinement was readily achievable for both alloys. Fe- and Al-rich intermetallic particles were observed in many magnesium grains.