[en] The dielectric relaxation in polar liquids is described in terms of an approximation which is equivalent to that used by Percus and Yevick in their theory of the liquid state. The formulation obtained in this way contains as a limiting case the theory of the static dielectric constant developed by the author in a previous paper. The final equation of the theory, when applied to the interpretation of an experimental Cole-Cole plot, can be used to get the polarizability and the permanent dipole moment of a polar molecule. For chlorbenzene, the resulting dipole moment is consistent with the indications of vapour phase data. On the contrary, the value predicted by an analogous calculation based on the Fatuzzo-Mason theory is much lower than the experimental one. The theory is also shown to predict the existence of collective modes, in agreement with the results obtained by Lobo, Robinson and Rodriguez (1973)