Polycrystalline LiBH4 has been studied by Raman spectroscopy in the temperature interval 295–412 K and the frequency range 2700–130 cm−1. The Raman active modes are consistent with the presence of a (BH4)− ion having a distorted tetrahedral configuration. As the temperature is increased the sudden disappearance of mode splitting points to the onset of a structural phase transition that leads to a higher local symmetry of the (BH4)− tetrahedron. The transition occurs at 384 K, is of first-order and has a hysteresis of about 8 K. A strong and discontinuous broadening of bands remaining after the transition suggests the onset of large vibrational amplitudes of the (BH4)− tetrahedra about their trigonal axis.