Optical anisotropy of the oriented poly(vinylidene f luoride) films formed by melt extrusion and porous films obtained by two-stage extension of annealed extruded samples is investigated. The difference in the refractive indices of light polarized in two mutually orthogonal planes is determined by the change in the polarization of light as it passes through the films. The transmission of light in both polarization directions is measured.