The radical polymerization of the three kinds of fluorine-containing maleimides, that is, N-[2-(trifluoromethyl) phenyl] maleimide (2TFPhMI), N-[3-(trifluoromethyl)phenyl] maleimide (3TFPhMI), and N-[4-(trifluoromethyl) phenyl]maleimide (4TFPhMI) was carried out in the presence of a radical initiator in benzene at 60 degrees C. The polymerization reactivity of these fluorine-containing maleimides and the properties of the resulting polymers were examined in comparison with the results for the methyl-substituted phenylmaleimides. The trifluoromethyl-substituted maleimides readily polymerized to give polymers in high yields as well as a methyl-substituted one. The resulting polymers showed an excellent resistance against organic solvents; especially, poly(4TFPhMI) was insoluble in the most common solvents. The onset temperature of thermal decomposition of the fluorine-containing polymers (T-int = 352-368 degrees C) was similar to that of poly(N-phenylmaleimide) (T-init = 364 degrees C) and slightly lower than those for the methyl-substituted one (T-init = 388-402 degrees C). The glass transition temperature of the polymers was dependent on the position of the trifluoromethyl group.