The relative surface energy of a 90° domain wall in a cubic material withK1>0 (iron) has been evaluated over the range of possible wall orientations. As the plane of the wall passes through a {110} plane, the minimum‐energy configuration changes from a right‐hand to a left‐hand rotation of the atomic moments; this leads to a sharp upward cusp in the energyvsorientation curve. The calculated orientation dependence of the surface energy can be used to predict a stable wall position in an iron whisker. The prediction is in reasonable agreement with observation.