The elastic constants of GaN have been determined using Brillouin scattering; in GPa they are:C11=390,  C33=398,  C44=105,  C66=123,  C12=145,  and   C13=106. Our values differ substantially from those quoted in the literature which were obtained from the determination of mean square displacement of atoms measured by x‐ray diffraction. ©1996 American Institute of Physics.