Abstract: Method of manufacturing large polycrystalline plates from optical and scintillation materials consists in heating a crystalline blank up to the temperature of 0,5T.sub.melt. <T<T.sub.melt., where T.sub.melt. -melting temperature of the starting material, as well as thermomechanical deformation by means of profiled surface up to the double thickness of the plate to be obtained, after which the blank is deformed again at the same temperature using flat-parallel surface till the specified thickness. Such technology provides the obtaining of large polycrystalline plates of the specified geometrical form with the necessary sizes.