The dielectric properties of three structurally related mesogenic compounds [4'-n-propyl phenyl-4-(4'-n-pentyl cyclohexyl) benzoate (code name HP53), trans-4-propyl cyclohexyl-4-(trans-4-pentyl eyclohexyl) benzoate (code name HH53), and 4-pentyl cyclohexyl-4-(4-propyl cyclohexyl) benzoate (code name HD35)] have been studied as a function of temperature, and their effective molecular dipole moments were determined. The effect of the operating frequency on the dielectric properties has been investigated and the thermal variation of the effective molecular dipole moment p in the mesophase studied. The dependence of beta, the angle of inclination of the dipole axis with the preferred direction on temperature, has been investigated.