When a magnetized tape in an oppositely directed field is rubbed, the stress &sgr; reduces the switching field by an amount &Dgr;H&sgr;so as to produce a partial reversal of the magnetization &Dgr;MH,&sgr;. This inverse magnetostrictive effect leads to the playback loss &Dgr;L that is observed in a recorded tape. The loss depends on &Dgr;H&sgr;, the coercive force Hc, the demagnetizing field and the shape of the hysteresis loop. The parameter &Dgr;H&sgr;is proportional to &sgr; and is related to the magnetostriction constants. It can exceed 300 Oe or greater than one half the coercive force in a 3.5&percent; Co‐doped &ggr;‐Fe2O3sample when &sgr;=500 kg/cm2. When Co is adsorbed on the surface of &ggr;‐Fe2O3particles the saturation magnetostriction ‖&ggr;s‖, &Dgr;H&sgr;and &Dgr;L are all smaller than for a Co‐doped tape with an equivalent Hc. The small &Dgr;L for CrO2is due to its low &lgr;swhereas low stress related losses in Fe are due primarily to a high Hc.