The frequency-wave-vector dispersion relation v(q) for the normal vibrations of a CuCl single crystal at room temperature has been measured for the [100]-, [110]~, and [lllj-symmetric directions using inelastic neutron scattering.In view of the interest in studying the lattice dynamics of crystals with zinc-blende structure, we present in this paper the results of coherent inelastic neutron scattering on cuprous chloride (CuCl). Our particular attention was drawn by this material because of its peculiar behavior relative to other crystals with the same symmetry, as pointed out by Martin. 1 The present experiments were performed by means of the triple-axis crystal spectrometer at 400-300 '200H 100-the EL3 reactor, Saclay. A collimated beam of monochromatic neutrons, produced by Bragg reflection from a germanium single crystal, was incident upon the CuCl specimen. The energies of the scattered neutrons were determined by Bragg reflection from a second germanium single crystal. The experiments were carried out by using either constant-Q or constant-v techniques, for waves propagating along the high-symmetry directions [lOO], [llO], and [ill]. 200-r=15min jM50-100-50 H y>-const"anl-= 20cm" TA [&S]Q-consfar^ = 0.6