The hypersonic elastic constants and the ratio of the elasto‐optic coefficients for two lead silicate optical‐grade glasses and for a zinc silicate optical‐grade glass have been obtained by observing the Brillouin scattering of 6328‐Å laser light over the temperature range 24–107 °C. Brillouin scattering at 90° from both the transverse and longitudinal acoustic modes has been observed. The values of the hypersonic Young's modulus and shear modulus agree with low‐frequency values and show a slight temperature dependence. Poisson's ratio and the ratio of the elasto‐optic coefficients are found to be independent of temperature over the temperature range used. There is no evidence of dispersion from audio to hypersonic frequencies.