Thermal annealing of damage‐induced strain in ion‐implanted epitaxial garnet films has been studied. The high strains typical of ion‐implanted propagation patterns decrease nearly linearly with the logarithm of annealing time (ln t), a functional dependence characteristic of thermally activated processes with a broad spectrum of activation energies. The theory of Vand, as extended by Primak, satisfactorily describes the data. In as‐implanted material, significant relaxation of the implantation strain is predicted for a device operating at 125 °C for several years. However, a stabilizing anneal for 30 min at 325–350 °C is adequate to assure 99% stability for 20 years at 125 °C. The required anneal is consistent with current design and fabrication practices.