Optical properties of polycarbonate plasticized by pentaerythritol tris(1,1,2,3,3,3-hexafluoropropyl) ether (HFP), diheptadecyl-o-phthalate and pentaerythrityl tetrabenzoate (TBP) have been determined at wavelengths from 300 to 700 nm. X-ray diffraction analysis, which was used to examine the polymer structure, showed that all the plasticized systems were amorphous. HFP and, especially, TBP impeded crystallization of the polymer. Plasticized polycarbonate films remained transparent over long periods of time even if they were heated at a temperature higher than the polymer glass transition temperature.