The temperature dependence of ferromagnetic resonance losses was measured for single‐crystal samples of lithium ferrite and yttrium iron garnet that were treated to increase or decrease the state of order of the atomic structure. The maximum linewidth, at low temperatures and caused by residual impurity ions, is much greater for the more ordered state as contrasted to the more disordered state. An explanation of these observations is given in terms of expected changes in the energy levels of the impurity ions with changes in the state of order.