Stereoscopic displays that use the viewing angle dependence of twisted nematic (TN) liquid crystal cells to direct light to either the left or right eye have been investigated. From a calculation that combined Frank's elastic theory and Berreman's 4 x 4 matrix method, it is observed that a luminance ratio defined as the luminance of viewing direction divided by that from the opposite direction largely depends on a pretilt angle of liquid crystal material and the cell thickness. The maximum luminance ratio is obtained at the cell thickness of the second-minimum. From experimental results, clear transmittance inversion between left and right directions observed, The experimental results of the viewing angle dependence are in good agreement with calculation results. The luminance ratios were 4.7 in the cell with polyimide alignment layer (the pretilt angle = 4.5 degrees) and 17 in the cell with alignment layer of SiO oblique evaporation (the pretilt angle = 40 degrees).