The static dielectric properties of the homologous series of liquid cyclic ethers, 12-crown-4, 15-crown-5, and 18-crown-6, were analyzed with the use of the electric modulus In isothermal conditions, the polarity of the ethers composed of the molecules with an even number of the oxygen atoms in the ring, 12-crown-4 and 18-crown-6, are quite similar to each other, whereas the odd number of the oxygen atoms in the ring of 15-crown-5 reflects itself in a considerable higher relative permittivity of the compound. It was shown that the observed permittivity behavior results chiefly from a different dipole moment of individual molecules of the ethers.