The effect of LC photo-aligning by (PVCi) derivatives is consequent to the phenomena of the photo-induced optical anisotropy, found in PVCi films during their illumination by UV-Iight within the self-absorption band of the PVCi film. We proved in our experiment, that the phenomena of the photo-induced birefringence in thin films of PVC derivatives takes place due to the two main factors: (i) described earlier irreversible photochemical process (2 + 2) cycloaddition of cinnamoyl groups and (ii) reversible photophysical reorientation of the chromophore groups, that accumulates photochemical non-active part of the UV-light energy. We reviewed various applications of the effect of photo-induced optical anisotropy in PVCi films including: (i) writing the polarization holograms and images, (ii) optical data processing, (iii) development of different polarization optical elements, (iv) non-destructive testing of defects, (v) LC photo-aligning. Most of the early papers, devoted to the above mentioned applications were published in 1977-1987 in USSR only and are not well known worldwide.