The paper reports on the effect of substituting Mn for Fe on the magnetostrictive and related properties of Fe 81−x Mn x Ga 19 alloys. Samples of composition were prepared in polycrystalline form and were all single phase BCC. It is shown that the magnetostriction observed in Fe 81 Ga 19 can be enhanced up to about 11% by Mn substitution with a maximum effect at x = 8. The change in the magnetostrictive coefficient of Fe 81 Ga 19 with Mn substitution is accompanied by a monotonic increase in resistivity, being increased by almost a factor of 2 for x = 8. We also found that the lattice parameter of the alloys increased with the increase in Mn concentration and the Curie temperature decreased monotonically at the same substitution.