Body centered cubic Fe_1−xBe_x alloys are known to display an enhanced tetragonal magnetostriction compared to Fe. In order to characterize the enhanced magnetoelasticity observed in this alloy system, we present detailed inelastic neutron scattering measurements of the phonon dispersion relations of a single crystal of bcc Fe, 10 at. %Be along the high symmetry directions [100], [110], and [111] at room temperature. We observe in particular that the frequency of transverse phonons propagating along the [110] direction with a [10] polarization at the zone boundary is reduced by 10% with respect to bcc Fe (the corresponding elastic shear constant c′ = ½(c₁₁−c₁₂) associated with this mode is approximately 70% that of pure Fe). The dispersion of spin waves has also been determined for energy transfers up to 40 meV and is found to follow the isotropic dispersion relation E(q) = Dq², with D ∼ 200 meV/Ų [for Fe, E(q) = Dq², with D = 280 meV/Ų].