The structural changes caused by explosive loading of a magnesium single crystal were investigated by using x‐ray Laue patterns, diffractometric measurements, and Fourier analysis of line profiles of x‐ray reflections. The results show that the magnesium single crystal was converted to polycrystalline metal with a high order of preferred orientation by explosive‐loading. The explosively loaded magnesium specimen consists of very small subgrains having an average size of about 500 Å. Experimental evidence tends to suggest that these subgrains are probably the result of instantaneous polygonization of an once highly strained, bent, and rotated lattice in the course of explosive‐loading. The residual strain associated with the subgrain structure is not as great as might be expected in view of the nature of loading.