A new transmission ellipsometric method-based on an eight-zone measurement-allows determination of birefringent properties of transparent systems and samples. In addition to well-known magnitudes (relative retardation Delta and polarization-dependent loss angle Psi) of reflection ellipsometry, two additional magnitudes-orientation of the optical axis phi and pseudoactivity angle rho-have to be ascertained. With a transmission ellipsometer working automatically on the basis of an eight-zone measuring method we attained resolution and reproducibility which is 1-2 decades better than that of commercial research reflection ellipsometers.