Photochemical behavior under the influence of UV-light of p-(methacryloyloxy)-N-phenylimides and their polymers was investigated. The possibilities of Friese photorearrangement (FPR) as for monomers so for polymers were studied. The velocity of FPR for phenyl methacrylate monomers depends weakly on the structure of imide substituents. But an introduction of substituents, especially of aromatic nature, in maleimide fragments increases the rate of FPR. For polymers with photoactive imide pendant groups both FPR and photocrosslinking reactions are possible. Correlations of velocities for crosslinkings and FPR reactions were found by the data of IR-spectroseopy. Photocrosslinking was found to be more rapidly process than FPR reaction.