Effect of &ggr;‐irradiation from Co60of radiation doze 50 MRad on the dielectric and thermodynamical properties of cholesteryl myristate (ChM) and cholesteryl pelargonate (ChP) have been studied by an electric impedance analyzer and differential scanning calorimeter (DSC). The mesophase transition temperatures, the enthalpy and the entropy of the transitions are depressed, and transition curves become asymmetric and wide on &ggr;‐irradiation. From the depressions in crystal to mesophase transition temperatures of ChM and ChP, we have estimated the molar fraction of impurity like fragments produced due to &ggr;‐irradiation of 50 MRad doze to be about 10%. Dielectric study of planar oriented samples of these two esters in the frequency range of 1 kHz to 10 MHz shows that due to &ggr;‐irradiation dielectric loss (&egr;‘) is increased by 50 to 150% in different mesophases while dielectric constant (&egr;’) is almost unchanged.