Zero magnetostrictive films about 1000 Å thick with cobalt contents from 0 to approximately 50 percent have been subjected to easy- and hard-axis saturating fields. The changes in characteristics were examined on aging for four hours in 30°C steps up to 240°C. Anisotropy field, dispersion, and coercive force were examined. The anisotropy and dispersion changes on aging indicated somewhat faster aging for samples with increasing cobalt. This is as expected for anM-induced annealing mechanism. However, the differences were small; maximum differences in the parameters, after aging to 150°C, between samples with different cobalt contents were ±10 percent.