The theory of Brillouin scattering of light in an optically anisotropic medium is developed. The influence of a uniform elastic strain on the intensity and the depolarisation factors of the light scattered by a glass are calculated. These quantities change rapidly when the forced birefringence reaches a magnitude of the same order as the optical fluctuations within the glass. They reach definite saturation values for large strains. The results are analogous in many respects to those observed for scattering in a graphite sol under the influence of a magnetic field.