Relative resonant displacement of bar magnetostrictors as a function of polarization at atmospheric stress and at a compressional, axial stress of 230 atm is measured. Laminated bars of nickel and 2V‐permendur are driven at frequencies both at and well below the resonant frequency of the bars, about 23 kc. Measurements of theQand the reversible permeability enable one to compare the magnetostrictive constants and the coupling at the two stress levels for both materials.The resonant displacement was found to change only slightly upon application of the compressive stress, for polarizing fields up to 100 oe. The compressive stress increased the maximum coupling for permendur by about 10%, the stress decreased the maximum coupling for nickel by about 10%.