Lithium niobate, LiNb0₃, is a universal ferroelectric material used for nonlinear-optical purposes. Lithium niobate crystals are usually grown along Z crystallographic axis using Czochralski technique. Unfortunately, crystals grown along X axis are characterized by a considerable fissuring and, thus, are not useable. This fissuring is the result of considerable internal stresses formed in crystals during their growth and cooling. A distribution of residual stresses in LiNb0₃ crystals grown along Z and X axes is studied herein using polarization-optical method, i. e. study of optical anomalies.