We report the findings of a new search for RR Lyraes in an M31 halo field located 40 arcminutes from the nucleus of the galaxy along the minor axis .
We detected 37 variable stars , of which 24 are classified as RR Lyraes and the others are ambiguous .
Estimating a completeness fraction of \sim 24 \% , we calculate that there are approximately 100 RR Lyraes in the field , which is consistent with what is expected from deep HST color-magnitude diagrams .
We calculate a mean magnitude of \langle g \rangle = 25.15 \pm 0.03 , which we interpret to mean that the mean metallicity of RR Lyraes is significantly lower than that of the M31 halo as a whole .
The presence of ancient , metal-poor stars opens the possibility that , initially , the M31 halo appeared much like the Milky Way halo .