The classical expression of the magnetoelastic energy of a monocrystal is transformed according to the most general rotation of the crystalline axes with respect to a given reference system. It is then possible to calculate the effect of a given stress on a polycrystalline material. It is shown that it is only for perfectly random crystallographic orientations that it is possible to cancel the ``macroscopic'' magnetostrictive effects of all the strains at the same composition for a magnetic alloy. If a cylindrical magnetic film with a preferential texture is made insensitive to an axial elongation, it will exhibit a magnetostrictive skew of its magnetic easy axis when the wire is twisted. The microscopic effects of stresses are also investigated in all cases: the so‐called ``isotropic stresses'' give a dispersion of the easy axis.