Flammability of Mg–X alloys was studied for X = Al, Ca, Si, Sn, Sr, La, Mn, Zn, Zr, Ce, Gd, and Nd. One end of a horizontal cylindrical specimen was subjected to a free diffusion liquid petroleum gas (LPG) flame. There was no burning without some melting of the specimen tip. Mg5%Gd, Mg3%Ca, and Mg5%Ca had considerable resistance to burning. Otherwise, on sufficient LPG flame exposure, there was melting and ignition of the specimen tip; any hot detached blob continued to burn until consumed, except for Mg1%Ca, Mg3%La, Mg3%Ce, and Mg5%Nd; and the burning specimen tip extinguished upon withdrawal of the applied LPG flame.