The pitch of the mixture MBBA:CC=22.7 :77.3 (by weight) at different tempera-lures ranging from 37℃ to 55℃ is determined by method of Bragg scattering using 6328? He-Ne laser beam. From the present measurement and the published data on other materials, we propose an empirical formula for the temperature dependence of the pitch of cholesterics, namely p=p0-b/(T-T0), with the pitch p0 for dextrorotatory materials. This formula is well suited not only for pure materials but also for mixtures as long as the temperature is not very close to the point of transition or the point of inversion of the helicity of the materials. The constants p0 ,b and T0 for different cholesteric liquid crystals are determined from their related data.