In the application of the Guinier‐Tennevin focusing Laue method to the study of crystal distortion, it is found that the use of a Soller slit in the incident beam produces striations in reflections from certain crystals. The diffraction geometry of a beam so modified is examined in detail, and it is shown that the striations are due to torsion of the crystal. The relation between the amount of torsion and the slope and spacing of the striations is treated quantitatively. There results a useful extension of the focusing Laue method by which not only the bending, but also the torsion, of a crystal may be measured.