Electro-optical properties of solutions of several cellulose esters in dioxane have been investigated. It was shown that macromolecules of these esters are characterized by high equilibrium and kinetic chain rigidity. The coincidence in signs of the Kerr and Maxwell effects in solutions of the samples reveals general relationships exhibited by all rigid-chain polymers for which the longitudinal geometric axis of the molecule (direction of the greater geometric length) is also the symmetry axis of its polar and optical properties. Experimentally found dependences of hydrodynamic and electro-optical properties of solutions of cellulose carbanilate (CC) on molecular weight (M//w) show that with the increase in M//w the conformation of the CC molecules varies from a faintly curved rod to a rigid Gaussian coil. At low M the transverse components of the monomer dipoles begin to play an important part in birefringence. 30 refs.